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in  Biolosical  Chemistry 


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A  TEXT-BOOK 


PHYSIOLOGICAL  CHEMISTRY. 


BY 


OLOF   HAMMARSTEN, 

PROFESSOR  OF  MEDICAL  AND   PHYSIOLOGICAL   CHEMISTRY  IN  THE 
UNIVERSITY    OF    UPSALA. 


§.ut^orx^jeb  translation 


FROM  THE  SECOND  SWEDISH  EDITION  AND  FROM  THE 

AUTHOR'S   ENLARGED   AND   REVISED 

GERMAN  EDITION 


JOHN    A.    MANDEL, 

ASSISTANT   TO   THE    CHAIR    OF   CHEMISTRY,  ETC.,  IN  THE 

BELLEVTJE   HOSPITAL    MEDICAL   COLLEGE   AND  IN 

THE  COLLEGE   OF    THE   CITY   OF   NEW   YORK. 


FIRST     EDITION. 
FIRST  THOUSAND. 


NEW  YORK : 

JOHN    WILEY    &    SONS, 

53  East  Tenth  Street. 

1893. 


fiAiif 


Copyright,  1893, 

BY 

JOHN  A.  MANDEL. 


ROBERT  DRUMM0N1>, 

Electrotyper, 

iU  &  446  Pearl  Street, 

New  York, 


THIS   TRANSLATION 

IS    RESPECTFULLY    DEDICATED    TO 

■WHO  GAVE  THE  IMPETUS   TO  THE   STUDY  OF  PHYSIOLOGICAL  CHEldSTRY 
BY  FOUNDING   THE   FIRST  CHEMICAL   LABORATORY  IN  CON- 
NECTION WITH   A   MEDICAL   COLLEGE   IN 
THIS   COUNTRY, 
BY  THE 

TRANSLATOR. 


PREFACE    TO    THE    GERMAN    EDITION". 


After  the  appearance  of  the  first  Swedish  edition  of  this  text- 
book, I  was  asked  by  several  co-laborers  abroad  to  provide  a  German 
translation,  which  was  at  that  time  impossible,  for  several  reasons. 
But  I  found  it  very  difficult  to  decline  a  similar  proposal  which  I 
received  from  many  colleagues  after  the  second  edition  appeared. 

I  yielded,  therefore,  to  their  expressed  wishes  ;  but  I  found  after 
a  time  that  it  was  impossible  to  obtain  a  translator  in  this  special 
province  of  science,  notwithstanding  the  unwearied  exertions  of  my 
publisher.  IsTothing  remained  for  me  but  to  undertake  the  trans- 
lation myself  :  hence  I  ask  the  reader's  indulgence  for  possible 
idiomatic  or  orthographic  errors. 

Specialists  will  at  once  perceive  that  the  book  before  us  is  not 
a  complete  or  detailed  text-book.  My  intention  was  merely  to 
supply  students  and  physicians  with  a  condensed  and  as  far  as  pos- 
sible objective  representation  of  the  principal  results  of  physiologico- 
chemical  research  and  also  with  the  principal  features  of  physio- 
logico-chemical  methods  of  work.  It  seems  to  me  that  I  have 
followed  a  common,  practical,  even  if  not  strictly  correct  usao-e  in 
allowing  space  in  this  book  to  the  more  important  pathologico- 
chemical  facts,  although  I  have  given  the  book  the  title  Text- 
book of  Physiological  Chemistry. 

The  arrangement  of  subject-matter,  which  deviates  considerably 
from  that  generally  followed  in  text-books,  was  caused  by  the 
manner  in  which  physiological  chemistry  is  studied  in  Sweden. 
Here  physiologico-  and  pathologico-chemical  laboratory  practice  is 
obUgatory  for  all  students  of  medicine.  In  the  arrangement  of 
such  practical  work  I  continually  kept  in  view  that  it  should  not 


VI  PREFACE  TO   THE  GERMAN  EDITION. 

consist  of  isolated,  purely  cliemical  or  analytico-chemical  problems, 
but  that  always,  as  far  as  possible,  it  should  go  hand  in  hand  with 
the  study  of  the  different  chapters  of  chemical  physiology. 

The  study  of  physiologico-chemical  processes  within  the  animal 
body  must  precede  the  study  of  its  component  parts,  its  fluids  and. 
tissues;  and  this  latter  study,  according  to  my  experience,  will  then 
only  inspire  true  interest  if  the  study  of  the  physiological  signifi- 
cance of  those  component  parts  be  closely  pursued  in  connection 
with  that  of  the  transformations  which  take  place  in  these  fluids 
and  tissues. 

In  view  of  this  arrangement  of  subject-matter,  and  in  order  to 
render  my  book  of  greater  interest  and  utility  to  those  who  do  not 
wish  to  take  cognizance  of  its  analytico-chemical  part,  I  have  dis- 
tinguished the  latter  by  different  setting  of  the  type.  With  the  excep- 
tion of  urinary  analysis,  which  practically  is  of  particular  impor- 
tance and  which  has  been  treated  somewhat  elaborately,  this  part  in 
general  depicts  only  the  main  points  in  the  methods  of  preparation 
and  of  analytical  methods.  The  instructor  who  superintends  the 
laboratory  practice  and  who  chooses  the  problems  for  work  has 
ample  opportunity  to  give  the  beginner  the  necessary  advanced 
directions,  and  for  the  more  experienced  student,  as  well  as  for  the 
specialist,  the  excellent  works  of  Hoppe-Setler,  Neubauer-Hup- 
PERT,  and  others  render  more  explicit  directions  superfluous. 

Olof  Hammarstejst. 
Upsala,   October,  1890. 


TRANSLATOR'S   PREFACE. 


Knowing  the  demands  of  the  medical  student  and  practising 
physician  for  a  more  extended  knowledge  of  physiological  chem- 
istry, and  at  the  same  time  knowing  the  lack  of  literature  on 
this  subject  in  the  English  language,  I  have  been  led  to  make  a 
translation  of  this  most  admirable  work.  The  subject  of  physiological 
chemistry  is  being  more  and  more  advanced  in  this  country,  until  it 
will  soon  become  an  obligatory  study  in  our  medical  schools,  and 
the  enlargement  of  the  literature  on  the  subject  will  greatly  help  its 
progress. 

It  will  be  seen  at  a  glance  that  the  work  is  well  suited  as  a 
laboratory  book,  for  it  contains  the  best  methods  for  the  prepara- 
tion, detection,  and  quantitative  estimation  of  most  of  the  substances 
found  in  the  organism  and  its  excretions  and  secretions.  At  the 
author's  request  I  have  made  no  additions  or  changes  whatsoever  in 
the  manuscript,  and  it  may  appear  that  some  of  the  methods  de- 
scribed, especially  on  the  urine,  are  too  lengthy  and  troublesome 
for  the  practising  physician;  still  the  quick  or  clinical  methods  are 
well  described  in  smaller  hand-books  on  the  subject.  In  the  work 
of  translation  I  have  adhered  as  closely  as  possible  to  the  author's 
enlarged  German  edition  and  also  the  original  Swedish  edition, 
and  therefore  the  literary  errors  will  perhaps  be  pardoned. 

I  mnst  here  express  my  appreciation  to  Mon.  A.  Bourgougnon 
who  has  kindly  gone  carefully  over  the  manuscript  and  read  the 
proof-sheets. 

J.  A.  Mandel. 
New  York,  October,  1893. 


CONTENTS. 


CHAPTER  I. 

PAGE 

Introduction 1 


CHAPTER  II. 
The  Protein  Substances 13 

CHAPTER  III. 
The  Animal  Cell 41 

CHAPTER  IV. 
The  Blood 54 

CHAPTER  V. 
Chyle,  Lymph,  Transudations  and  Exudations 117 

CHAPTER  VI. 
The  Liver I35 

CHAPTER  VII. 
Digestion. 167 

CHAPTER  VIIL 

Tissues  of  thb  Connective  Substance 333 

ix 


X  CONTENTS. 

CHAPTER  IX. 

PAGE 

Muscle,...  .' 251 

CHAPTER  X. 
Brain  and  Nerves 273 

CHAPTER  XI. 
Organs  of  Generation 285 

CHAPTER  XII. 
Milk 300 

CHAPTER  XIII. 
The  Skin  and  its  Secretions 322 

CHAPTER  XIV. 
The  Urine 330 

CHAPTER  XV. 
The  Exchange  OP  Material 435 


PHYSIOLOGICAL    CHEMISTRY. 


CHAPTER  I. 
INTRODUCTION. 

It  follows  from  the  law  of  the  conservation  of  force  and  matter 
that  living  beings,  plants  and  animals,  can  neither  produce  new 
matter  nor  new  force.  They  are  only  called  upon  to  appropriate 
and  assimilate  already  existing  material  and  to  transform  it  into 
new  forms  of  force. 

Out  of  a  few  relatively  simple  combinations,  especially  carbon 
dioxide  and  water,  together  with  ammonium  compounds  or  nitrates, 
and  a  few  mineral  substances,  which  serve  as  its  food,  the  plant 
builds  up  the  extremely  complicated  constituents  of  its  organism, 
albumins,  carbohydrates,  fats,  resins,  organic  acids,  etc.  The 
chemical  work  which  is  performed  in  the  plant  must  therefore,  iii 
the  majority  of  cases,  consist  in  syntheses;  but  besides  these, 
processes  of  reduction  take  place  to  a  great  extent.  The  vis  viva 
of  the  sunlight  induces  the  green  parts  of  the  plant  to  split  off  oxy- 
gen from  the  carbon  dioxide  and  water,  and  therefore  the  chief 
constituents  of  the  plant  contain  less  oxygen  than  the  material  serv- 
ing as  food.  The  vis  viva  of  the  sun,  which  produces  this  splitting, 
is  not  lost;  it  is  only  transformed  into  another  form  of  force,  into 
the  potential  energy  or  chemical  tension  of  the  free  oxygen  on  the 
one  side  and  the  combinations  less  oxygenated  produced  by  the 
synthesis,  on  the  other  side. 

These  conditions  are  not  the  same  in  animals.  They  are  de- 
pendent either  directly,  as  the  herbivora,  or  indirectly,  as  the  car- 


2  PHYSIOLOGICAL  CHEMI8TBT. 

nivora,  upon  plant-life,  from  which  they  derive  the  three  chief 
groups  of  organic  nutritive  matter — proteids,  carbohydrates,  and 
fat.  These  bodies,  of  which  the  protein  substances  and  fat  form 
the  chief  mass  of  the  animal  body,  undergo  within  the  animal 
organism  a  splitting  and  oxidation,  and  yield  as  final  products  ex- 
actly the  above-mentioned  chief  components  of  the  nutrition  of 
plants,  namely,  carbon  dioxide,  water,  and  ammonia  derivatives, 
which  are  rich  in  oxygen  and  have  a  feeble  chemical  tension.  The 
chemical  tension,  which  is  partly  combined  with  the  free  oxygen 
and  partly  stored  up  in  the  above-mentioned  more  complex  chemi- 
cal compounds,  is  transformed  into  vis  viva,  heat,  and  mechanical 
work.  While  in  the  plant  reduction  processes  and  syntheses,  which 
are  active  in  the  conversion  of  living  force  into  potential  energy  or 
chemical  tension,  are  the  prevailing  forces,  we  find  in  the  animal 
body  the  reverse  of  this,  namely,  splitting  and  oxidation  processes, 
which  convert  chemical  tension  into  living  force  {vis  viva). 

This  difference  between  animals  and  plants  must  not  be  over- 
rated, nor  must  we  consider  that  there  exists  a  sharp  boundary-line 
between  the  two.  This  is  not  the  case.  There  are  not  only  lower 
plants,  free  from  chlorophyll,  which  in  regard  to  chemical  processes 
represent  intermediate  steps  between  higher  plants  and  animals, 
but  the  difference  existing  between  the  higher  plants  and  animals 
is  more  of  a  quantitative  than  a  qualitative  kind.  Plants  require 
oxygen  as  peremptorily  as  do  animals.  Like  the  animal,  the  plant 
also,  in  the  dark  and  by  means  of  those  parts  which  are  free  from 
chlorophyll,  takes  up  oxygen  and  eliminates  carbon  dioxide,  while 
in  the  light  the  oxidation  processes  going  on  in  the  green  parts  are 
overshadowed  or  hidden  beneath  the  more  intense  reduction  pro- 
cesses. Like  the  animal  the  vegetable  ferments  transform  chemi- 
cal tension  into  living  energy  and  heat;  and  even  in  a  few  of  the 
higher  plants — as  the  aroidecB  when  bearing  fruit — a  considerable 
development  of  heat  has  been  observed.  The  reverse  is  found  in 
the  animal  organism,  for,  besides  oxidation  and  splitting,  reduction 
processes  and  syntheses  also  take  place.  The  contrast  which 
seemingly  exists  between  animals  and  plants  consists  merely  in 
that  in  the  animal  organism  the  processes  of  oxidation  and  split- 
ting are  prevalent,  while  in  the  plant  those  of  reduction  and  syn- 
thesis have  mostly  been  observed. 


INTRODUCTION.  3 

WoHLEE  in  1834  furnished  the  first  example  of  synthetical 
PEOCESSES  within  the  animal  organism.  He  showed  that  when 
benzoic  acid  is  introduced  into  the  stomach  it  reappears  as  hippuric 
acid  in  the  urine,  after  its  coupling  with  glycocoll  (amido-acetic 
acid).  Since  the  discovery  of  this  synthesis,  which  may  be  ex- 
pressed by  the  following  equation, 

C,H,.COOH  +  NH,.CH,.COOH=NH(C,H,.CO).CH,.COOH+H,0, 

Benzoic  acid  Glycocoll  Hippuric  acid 

and  which  is  ordinarily  considered  as  a  type  of  an  entire  series  of 
syntheses  occurring  in  the  body  where  water  is  eliminated,  the 
number  of  known  syntheses  in  the  animal  kingdom  has  increased 
considerably.  Many  of  these  syntheses  have  also  been  artificially 
produced  outside  of  the  organism,  and  numerous  examples  of  ani- 
mal syntheses  of  which  the  history  is  absolutely  clear  will  be  found 
in  the  following  pages.  Besides  these  well-studied  syntheses, 
there  occur  in  the  animal  body  also  similar  processes  unques- 
tionably of  the  greatest  importance  to  animal  life,  but  of  which  we 
know  nothing  with  positiveness.  We  enumerate  as  examples  of 
this  kind  of  synthesis  the  new  formation  of  the  red  blood-corpus- 
cles (the  haemoglobin),  the  formation  of  the  different  albumins 
from  the  peptones,  the  formation  of  fat  from  carbohydrates,  and 
others. 

The  chemical  processes  in  the  animal  body  we  have  mentioned 
above  as  consisting  chiefly  of  oxidation  and  splitting  processes. 
The  oxygen  of  inhaled  air,  as  also  that  of  the  blood,  is  now  called 
neutral,  molecular  oxygen,  and  the  old  assumption  that  ozone  occurs 
in  the  organism  has  now  been  discarded  for  several  reasons.  There 
are  few  substances  which  can  be  introduced  from  the  outside,  such 
as  aldehydic  compounds  and  certain  alcohols,  for  example  benzyl- 
alcohol  (Schmiedeberg),  which  can  be  oxidized  within  the  animal 
organism  by  the  neutral  oxygen ;  while,  on  the  contrary,  albumin 
and  fat,  which  form  the  chief  part  of  the  organic  constituents  of 
the  animal  body,  are  almost  indifferent  to  neutral  oxygen.  The 
question  arises,  how  then  is  the  oxidation  of  these  and  other  bodies 
possible  in  the  animal  organism  ? 

Formerly  the  view  was  generally  accepted  that  ai^imal  oxida- 
tion took  place  in  the  animal  fluids,  while  to-day  we  are  of  the 


4  PHYSIOLOGICAL  CHEMISTRY. 

opinion  that  it  is  connected  with  the  form-elements  and  the  tis- 
sues. The  question  how  this  oxidation  in  the  form-elements  pro« 
ceeds  and  how  it  is  induced  cannot  be  answered  with  certainty. 

In  conformity  with  the  views  of  Pfluger  and  others,  it  is  often 
asserted  that  the  albumin  outside  of  the  organism,  and  also  that 
which  circulates  in  the  blood  and  fluids, is  to  be  regarded  as  "dead 
albumin,"  as  distinguished  from  that  which  is  converted  by  the  work 
of  the  living,  active  cell  into  living  protoplasm — "living  albumin.'^ 
The  statement  has  also  been  made  that  this  living  protoplasm 
albumin  is  differentiated  from  the  "  dead  albumin "  by  a  greater 
mobility  of  the  atoms  within  the  molecule,  and  it  may  be  char- 
acterized by  a  greater  inclination  towards  intramolecular  changes 
of  position  of  these  atoms.  The  reason  for  this  greater  inner 
movement  Pflugee  ascribes  to  the  presence  of  certain  groups, 
such  as  cyanogen,  while  Loew  attributes  it  to  the  presence  of  alde- 
hydic  groups  in  the  albumen  molecule. 

In  these  differences  between  ordinary  albumins  and  living 
protoplasm  albumin  Pfltjger  sees  the  reason  for  the  animal  oxi- 
dation processes  which  show  certain  similarity  to  the  oxidation  of 
phosphorus  in  air  containing  oxygen.  In  the  last-mentioned 
process  the  phosphorus  is  not  only  itself  oxidized,  but,  as  it  splits 
the  oxygen  molecule  and  sets  free  oxygen  atoms  (active  oxygen), 
it  may  also  have  at  the  same  time  an  indirect  or  secondary 
oxidizing  action  upon  other  bodies  present.  In  an  analogous  way 
the  living  protoplasm  albumin,  which  is  not,  like  the  dead  albu- 
min, indifferent  to  neutral  oxygen,  can  disintegrate  the  oxygen 
molecule,  thus  becoming  itself  oxidized,  and  at  the  same  time  the 
setting  free  of  oxygen  atoms  may  cause  a  secondary  oxidation  of 
other  less  oxidizable  substances. 

Another  very  widely-diffused  view  exists  in  regard  to  the  origin 
of  the  activity  of  the  oxygen,  so  that  by  the  decomposition  pro- 
cesses in  the  tissues  reducing  substances  are  formed  which  split 
the  neutral  oxygen  molecule,  uniting  with  one  oxygen  atom  and 
setting  the  other  free. 

The  formation  of  reducing  substances  by  fermentation  and 
putrefaction  is  generally  known.  The  butyric  fermentation  of 
sugar  in  which  hydrogen  is  set  free — C^Hj^Og  =  C^HgO,  +  300, 
-j-  2(HJ — is  an  example  of  this  kind.     Another  example  is  the 


INTRODUCTION.  6 

appearance  of  nitrates  in  consequence  of  an  oxidation  of  nitrogen 
in  cases  of  putrefaction,  which  process  is  ordinarily  explained  by 
the  statement  that,  in  putrefaction,  reducing,  easily-oxidizable 
bodies  are  formed  which  split  oxygen  molecules,  liberating  oxygen 
atoms  which  afterward  oxidize  the  nitrogen.  It  is  assumed  also  that 
the  cells  of  the  animal  tissues  and  organs,  like  these  lower  organ- 
isms, which  cause  fermentation  and  putrefaction,  undergo  such 
splitting  processes  in  which  easily-oxidizable  substances,  perhaps 
also  hydrogen  in  statu  7iascencli  (Hoppe-Seylek),  are  produced. 
The  observations  of  Ehklich,  that  certain  blue  coloring  matters — 
alizarin  blue  and  indophenol  blue — are  decolorized  by  the  tissues  of 
the  living  animal  and  become  blue  again  on  exposure  to  air,  seem 
also  to  be  a  proof  of  the  occurrence  of  easily-oxidizable  combina- 
tions in  the  tissues.  A  further  proof  of  this  is  found  in  the  obser- 
vations of  0.  LuDwiG  and  Alex.  Schmidt  that  in  the  blood  of 
asphyxiated  animals,  as  well  as  in  the  absence  of  oxygen,  an  accu- 
mulation of  reducing,  easily-oxidizing  substances  takes  place. 

In  accordance  with  what  has  been  above  stated,  we  may  assume 
that  the  oxidation  in  the  animal  body  takes  place  in  the  following 
manner:  The  forces  peculiar  to  protoplasm,  unknown  to  us,  but 
acting  similarly  to  heat,  increase  the  intramolecular  movements  of 
the  atoms  in  such  a  way  that  a  loosening  or  splitting  of  the 
molecule  occurs  and  an  aggregation  of  the  oxygen  is  made  possible 
("primary  oxidation,"  Nasse).  The  new  products  formed  in  this 
manner  may  perhaps  in  part  be  in  direct  combination  with  neutral 
oxygen  ("  direct  oxidation,"  Nasse)  and  gradually  burned  within 
the  body,  but  they  must  probably  first  undergo  a  further  splitting, 
and  then  succumb  to  consecutive  oxidation,  until,  after  repeated 
splitting  and  oxidation,  the  final  products  of  the  exchange  of 
material  are  formed.  Finally,  the  easily-oxidizable  products  of 
decomposition,  when  they  split  the  oxygen  molecule  and  only 
combine  with  one  of  the  oxygen  atoms,  may  act  on  difficultly- 
oxidizable  substances  in  an  indirect  or,  as  Nasse  has  called  it,  a 
■"secondary  oxidation"  by  the  setting  free  of  the  second  atom. 

Thus  the  oxidation  within  the  animal  body  is  caused  by  the 
action  of  forces  acting  similarly  to  heat,  which  loosens  or  splits  the 
molecules;  and  since  this  oxidation  has  long  been  known  as  com- 
bustion, this  view  is  easily  reconcilable  with  the  mode  of  action 


6  PEYSIOLOOICAL   CHEMISTRY. 

just  described.  In  combustion  in  the  ordinary  sense,  as,  for 
example,  the  burning  of  wood  or  oil,  we  must  not  forget  that 
the  substances  themselves  do  not  combine  with  oxygen.  It  is 
only  after  the  action  of  heat  has  decomposed  these  bodies  to  a 
certain  degree  that  the  oxidation  of  the  products  of  such  decom- 
position takes  place  and  is  accompanied  by  the  phenomenon  of 
light. 

The  numerous  intermediary  products  of  decomposition  which 
we  observe  in  the  animal  body  teach  us  that  the  oxidations  and 
splittings  of  the  components  of  the  body  do  not  take  place  at  once 
and  suddenly,  but  only  very  gradually,  step  by  step,  until  the  final 
products  of  exchange  are  reached. 

A  very  instructive  example  of  such  a  gradual  decomposition 
outside  of  the  organism  has  been  shown  by  Deechsel  in  his  in- 
vestigation on  the  electrolysis  of  phenol  by  an  alternating  current. 
By  experiments  with  alternating  electric  currents  we  obtain,  of 
course,  in  the  watery  solution  of  the  substance,  at  each  electrode 
alternately,  oxygen  and  hydrogen  in  great  rapidity.  Therefore 
oxidations  and  reductions  must  take  place  alternately,  and  we  ob- 
tain syntheses  as  wdl  as  splittings  with  oxidations. 

If  phenol  in  watery  solution  is  treated  with  such  an  alternating 
current,  we  produce,  by  the  combined  action  of  reduction  and 
oxidation  processes,  where  all  double  linking  in  the  benzol  ring  is 
broken  by  the  aggregation  of  hydrogen  atoms  with  simultaneous 
solution,  and  followed  by  an  oxidation  with  the  elimination  of 
hydrogen  atoms,  a  new  body,  hydro-phenoketon,  CgHj„0,  or 
CH, 

5^rll       (nxT  •     From  the  hydro-phenoketon  a  compound  of  the 


CH, 

fatty  series  is  produced  by  the  fixation  of  0  +  3H  accompanied 
with  the  splitting  of  the  benzol  ring,  namely,  normal  caproic  acid, 
CH, 

C.Hj^O,,  or  S'nl      JcH^"^-     -^y  further  electrolysis  of  the  ca- 

CH, 

proic  acid,  with  the  removal  of  carbon  as  carbon  dioxide  and  of 


INTRODUCTION.  7 

hydrogen  as  water,  a  series  of  acids  with  decreasing  amounts  of 
carbon  are  obtained,  and  in  this  way  we  may,  by  properly  directed 
combination  of  reductions  and  oxidations,  pass  from  a  body  of  the 
aromatic  series  to  a  body  of  the  fatty  series,  and  then  to  substances 
in  which  the  amount  of  carbon  decreases,  until  the  final  products 
of  animal  exchange  are  reached. 

That  reduction  processes  occur  in  the  organism  has  already  been 
stated,  and  in  the  following  pages  special  examples  of  these  are 
given.  As  Drechsel  has  also  found  that  the  same  electro-syn- 
theses (of  urea  and  phenol-sulphuric  acid)  are  produced  by  the 
continuous  as  well  as  by  the  alternating  current,  and  since  the 
occurrence  of  galvanic  currents  in  the  body  has  been  positively 
shown,  Drechsel  concludes  that  not  only  do  syntheses,  but  also 
the  combustion  of  foods  and  constituents  of  the  tissues,  take  place 
in  the  animal  body  in  consequence  of  a  quick  succession  of  reduc- 
tions and  oxidations. 

Another  attempt  to  explain  the  animal  oxidations  has  been 
made  by  M.  Traube.  Traube  has  brought  forward  powerful 
arguments  against  the  view  that  an  activity  of  the  oxygen  is  caused 
by  reducible  substances,  and  he  seems  to  believe  that  within  the 
organism  so-called  oxygen  transmitters  occur  which  act  similarly 
to  nitric  oxide  in  the  manufacture  of  sulphuric  acid  where  oxida- 
tion is  the  result  of  the  absorption  and  liberation  of  oxygen  by 
other  substances  which  are  themselves  not  directly  oxidized  by 
neutral  oxygen.  The  presence  of  such  bodies  in  the  animal  organ- 
ism has  not  thus  far  been  proved. 

An  important  source  of  the  vis  viva  developed  in  the  body  is  to 
be  sought  for  in  the  oxidation  derived  from  oxygen  of  strong  poten- 
tial energy,  but  also  in  the  splitting  processes  ;  where  more  com- 
plicated chemical  compounds  are  reduced  to  simpler  ones,  and 
when,  therefore,  the  atoms  change  from  a  movable  equilibrium  to 
a  stabler  one  and  stronger  chemical  affinities  are  satisfied,  the  chem- 
ical potential  energy  is  transformed  into  vis  viva  (or  living  energy). 
The  best-known  examj^le  of  such  a  splitting  process  outside  of  the 
animal  organism  is  the  ordinary  alcoholic  fermentation  of  sugar, 
C,H,,0„  =  2C0,  +  2C,H,0,  in  which  process  heat  is  set  free.  The 
animal  body  may  also  have  a  source  of  vis  viva  in  the  splitting 
processes  which  are  not  dependent  on  the  presence  of  free  oxygen. 


8  PHYSIOLOGICAL   CHEMISTRY. 

The  processes  taking  place  in  the  living  muscle  yields  an  example 
of  this  kind.  A  removed  muscle,  which  gives  no  oxygen  when  in 
a  vacuum,  may,  as  Hermann  has  shown,  work,  at  least  for  a  time,  in 
an  atmosphere  devoid  of  oxygen,  and  give  off  carbon  dioxide  at  the 
same  time. 

We  call  processes  of  splitting  which  are  accompanied  by  a  de- 
composition of  water  and  then  a  taking  up  of  its  constituents  (H, 
and  0)  hydrolytic  splittings.  These  splittings,  which  play  an  im- 
portant role  within  the  animal  body,  and  which  are  most  frequently 
met  with  in  the  process  of  digestion,  are,  for  example,  the  trans- 
formation of  starch  into  sugar  and  the  splitting  of  neutral  fats  into 
the  corresponding  fatty  acid  and  glycerin. 

C3H,(C,,H3,0J3  +  3  H,0  =  C3H,(OH)3  +  3(C,,H3A). 

Tristearin.  Glycerin.  Stearic  acid. 

As  a  rule  the  hydrolytic  splitting  processes  as  they  occur  in  the 
animal  body  may  be  performed  outside  of  it  by  means  of  higher 
temperatures  with  or  without  the  simultaneous  action  of  acids  or 
alkalies.  Considering  the  two  above-mentioned  examples,  we  know 
that  starch  is  converted  into  sugar  when  it  is  boiled  with  dilute 
acids,  and  also  that  the  fats  are  split  into  fatty  acids  and  glycerin 
on  heating  them  with  caustic  alkalies  or  by  the  action  of  super- 
heated steam.  The  heat  of  the  chemical  reagents  which  are  used 
for  the  performance  of  these  reactions  would  cause  immediate 
death  if  applied  to  the  living  system.  Consequently  the  animal 
organism  must  have  other  means  at  its  disposal  which  will  act 
similarly,  but  in  such  a  manner  that  they  may  work  without 
endangering  the  life  or  normal  constitution  of  the  tissues.  Such 
means  have  been  recognized  in  the  so-called  formless  ferments  or 
enzymes. 

Alcoholic  fermentation,  as  well  as  other  processes  of  fermenta- 
tion and  putrefaction,  is  dependent  upon  the  presence  of  living 
organisms,  ferment  fungi  and  splitting  fungi  of  different  kinds;  and 
according  to  the  researches  of  Pasteur,  these  processes  are  to  be 
considered  as  phases  of  life  of  these  organisms.  The  name  orga- 
nized ferments  or  ferm.ents  has  been  given  to  such  micro-organisms 
of  which  ordinary  yeast  is  an  example.  However,  the  same  name  has 
also  been  given  to  certain  bodies  or  mixtures  of  bodies  of  unknown 


INTRODUCTION.  9 

organic  origin  which  are  products  of  the  chemical  work  within 
the  cell,  and  which,  after  they  are  separated  from  the  cell,  are 
capable  in  the  smallest  quantities  of  causing  a  decomposition  or 
splitting  in  very  considerable  quantities  of  other  substances  with- 
out entering  into  combination  with  the  decomposed  body  or  with 
any  of  its  products  of  splitting  or  decomposition.  Such  ferments 
are,  for  example,  the  diastase  of  malt  and  the  ferments  secreted  by 
the  different  glands  participating  in  the  process  of  digestion. 
These  non-organized  ov  formless  f elements  are  generally  called,  ac- 
cording to  KiJHNE,  enzymes. 

A  ferment  in  a  more  restricted  sense  is  therefore  a  living  being, 
while  an  enzyme  is  a  product  of  chemical  processes  in  the  cell,  a 
product  which  has  an  individuality  even  without  the  cell,  and 
which  may  be  active  when  separated  from  the  cell.  The  splitting 
of  glucose  or  invert-sugar  into  carbon  dioxide  and  alcohol  by  fer- 
mentation is  a  fermentative  process  closely  connected  with  the  life 
of  the  yeast.  The  inversion  of  cane-sugar  is,  on  the  contrary,  an 
enzymotic  process  caused  by  one  of  the  bodies  or  mixture  of  bodies 
formed  by  the  living  ferment,  which  can  be  severed  from  this  fer- 
ment, and  still  remains  active  even  after  the  death  of  the  latter. 
Consequently  ferments  and  enzymes  are  capable  of  manifesting  a 
different  behavior  towards  certain  chemical  reagents.  Thus  there 
exist  a  number  of  substances,  among  which  we  may  mention  arse- 
nious  acid,  phenol,  salicylic  acid,  boracic  acid,  chloroform,  ether,  and 
others,  which  in  certain  concentration  kill  ferments,  but  which  do 
not  noticeably  impair  the  action  of  the  enzymes. 

It  is  doubtful,  indeed  highly  improbable,  whether  it  has  been 
possible  up  to  the  present  time  to  isolate  any  enzyme  in  a  pure  state. 
Therefore  the  nature  of  the  enzymes  and  their  elementary  compo- 
sition is  unknown.  Such  as  have  been  obtained  thus  far  appear  to 
be  nitrogenized  and  to  be  similar  in  some  degree  to  albuminous 
bodies.  They  may  be  extracted  from  the  tissues  by  means  of  water 
or  glycerin,  especially  by  the  latter,  which  forms  very  stable  solu- 
tions and  which,  consequently,  serves  as  a  means  of  extraction  of 
the  enzymes.  The  enzymes,  generally  speaking,  do  not  appear  to 
be  diffusible,  they  decompose  hydrogen  peroxide  and  are  precipi- 
tated with  other  substances  when  these  are  in  a  finely-divided  state. 
This  property  has  also  often  been  taken  advantage  of  in  the  i^repa- 


10  PHYSIOLOGICAL   CREMISTRT. 

ration  of  pure  enzymes.  The  continued  heating  of  their  solutions 
above  +  80°  C.  generally  destroys  most  of  the  enzymes.  In  the 
dry  state,  however,  certain  enzymes  may  be  heated  to  100°  or  indeed 
to  150°-160°  0.  without  losing  their  jjower.  The  enzymes  are  pre- 
cijDitated  from  their  solutions  by  alcohol. 

We  have  no  characteristic  reactions  for  the  enzymes  in  general, 
and  each  enzyme  is  characterized  by  its  specific  action  and  by  the 
conditions  under  which  it  develops.  But  it  must  be  stated  that, 
however  the  different  enzymes  may  vary  in  action,  they  all  seem  to 
have  this  in  common,  that  by  their  presence  an  impulse  is  given  to 
split  more  complicated  combinations  into  simpler  ones,  whereby  the 
atoms  arrange  themselves  from  an  unstable  equilibrium  into  a  more 
stable  one,  chemical  tension  is  transformed  into  living  force,  and 
new  products  are  formed  with  lower  heat  of  combustion  than  the 
original  substance.  The  presence  of  water  seems  to  be  a  necessary 
factor  in  the  perfection  of  such  decompositions,  and  the  chemical 
process  seems  to  consist  in  the  taking  up  of  the  elemejits  of  water. 
The  manner  in  which  these  enzymes  work  is  still  enveloped  in 
darkness,  but  their  action  may  be  considered  as  very  closely  related 
to  the  so-called  catalytic  or  contact  action. 

As  above  stated,  the  enzymes  are  of  great  importance  for  the 
chemical  processes  going  on  in  the  digestive  tract,  but  we  have  to 
add  that  the  results  of  their  action  is  greatly  complicated  by  pro- 
cesses of  putrefaction  which  take  place  in  the  intestines  at  the  same 
time,  and  which  are  caused  by  micro-organisms.  Micro-organisms 
are  physiological  constituents  of  the  contents  of  the  intestinal  canal, 
and  it  is  therefore  to  be  supposed  that  also  lower  organisms  or  their 
germs  are  to  be  encountered  in  the  animal  tissues  and  fluids  gen- 
erally, under  normal  conditions.  The  question  is  still  unsettled  as 
to  how  far  this  is  the  case.  But  as  yet  no  positive  or  decisive  proof 
for  the  justification  of  such  a  statement  has  been  furnished.  The 
lower  organisms,  on  the  contrary,  when  they  enter  into  the  animal 
fluids  or  tissues  and  develop  and  increase,  are  of  the  greatest  patho- 
logical importance,  and  modern  bacteriology,  founded  by  Koch 
and  Pasteuk,  in  relation  to  the  doctrine  of  infectious  diseases, 
gives  efficient  testimony  to  these  facts. 

Putrefaction  caused  within  the  animal  fluids  and  tissues  by  the 
lower  organisms  may  produce,  among  others,  combinations  of  a 


INTROD  UCTION.  1 1 

basic  nature.  Such  bodies  were  first  found  by  Selmi  in  human 
cadavers,  and  called  by  him  cadaver  alkaloids  or  ptomaines.  These 
ptomaines,  which  have  been  studied  by  a  great  number  of  investi- 
gators, especially  by  Selmi,  Beieger,  and  Gautier,  must  be  con- 
sidered as  products  of  chemical  processes  caused  by  putrefaction 
microbes.  Some  of  these  ptomaines  are  exceedingly  poisonous,  and 
consequently  Brieger  has  called  them  toxines. 

The  formation  of  such  poisonous  products  in  the  decompositions 
caused  by  putrefactive  microbes  makes  it  probable  that  the  lower 
organisms  acting  in  infectious  diseases  also  produce  poisonous  sub- 
stances which  may  cause  by  their  action  the  symptoms  or  compli- 
cations of  the  disease.  Brieger,  who  has  become  prominent  by 
his  study  of  this  subject,  has  been  able  to  isolate  from  typhus 
cultures  a  substance  called  typliotoxin  which  has  a  poisonous  action 
on  animals;  and  he  has  also  prepared  another  substance,  tetmiin, 
from  the  amputated  arm  of  a  patient  with  tetanus,  animals  inocu- 
lated with  which  die  exhibiting  symptoms  of  developed  tetanus. 
Admitting  that  the  results  obtained  thus  far  upon  this  subject  are 
not  very  numerous,  we  cannot  refrain  from  stating  that  the  facts  al- 
ready found  open  a  promising  field  for  further  labor  and  research. 

As  above  stated,  the  chemical  processes  in  animals  and  plants  do 
not  stand  in  opposition  to  each  other;  they  offer  differences  indeed, 
but  still  they  are  of  the  same  kind  from  a  qualitative  standpoint. 

PFLiJGER  says  that  there  exists  a  blood-relationship  between  all 
living  cells  of  the  animal  and  vegetable  kingdoms,  and  that  they 
originate  from  the  same  root ;  and  if  the  organisms  consisting  of  one 
cell  can  decompose  protein  substances  in  such  a  manner  as  to  pro- 
duce poisonous  substances,  why  should  not  the  animal  body,  which 
is  only  a  collection  of  cells,  be  able  to  produce  under  physiological 
conditions  similar  poisonous  substances  ?  The  poisonous  secretions 
of  toads,  serpents,  and  numerous  other  animals  prove,  in  fact,  that 
the  animal  body  has  this  power.  Frequent  efforts  have  been  made 
of  late  to  prove  that  the  human  organism  under  physiological  con- 
ditions produces  poisonous  substances.  In  the  human  saliva  (Gau- 
tier and  others),  and  especially  in  the  urine  (Pouchet,  Bouchard, 
and  others),  but  also  in  the  expired  air  (Brown-Sequard  and 
d'Arsonval),  poisonous  organic  substances  have  been  proved  to 
exist.     The  correctness  of  many  of  these  statements  is  contradicted 


12  PHYSIOLOGICAL   CHEMISTRY. 

by  other  investigators,  and  the  interesting  question  as  to  the  poison- 
ous nature  of  the  human  physiological  secretions  and  excretions 
seems  to  require  further  proof. 

The  so-called  leucomaines  command  a  special  interest.  Those 
substances  of  basic  nature  which  are  incessantly  and  regularly  pro- 
duced as  products  of  the  decomposition  of  the  protein  substances  of 
the  organism,  and  which  therefore  are  to  be  considered  as  products 
of  the  physiological  exchange  of  substance,  have  been  called  leuco- 
maines  by  Gautiek  in  contradistinction  to  the  ptomaines  produced 
by  micro-organisms.  These  substances,  with  the  exception  of  a 
few  which  were  known  in  animal  extractives,  were  first  found 
by  Gautier  in  animal  tissues  and  muscles,  and  among  these  he 
finds  some  which  are  poisonous  in  small  doses.  The  leucomaines 
of  late  are  considered  of  special  importance  as  originators  of  disease. 
It  has  been  contended  that  when  these  bodies  accumulate,  on  ac- 
count of  an  incomplete  excretion  or  oxidation  in  the  system,  an 
autointoxication  may  be  produced  (Bouchard).  Though  this 
view  is  not  by  any  means  based  upon  generally-recognized  facts, 
still  it  offers  an  interesting  starting-point  for  physiological  and 
pathological  chemical  research. 


CHAPTER  II. 
THE  PROTEIN   SUBSTANCES. 

The  chief  mass  of  the  organic  constituents  of  animal  tissues 
consists  of  amorphous,  nitrogenized,  complex  bodies  of  high  molecu- 
lar weight.  These  bodies,  which  are  either  albuminous  in  a  special 
sense  or  bodies  nearly  related  thereto,  take  first  rank  among  the 
organic  constituents  of  the  animal  body  on  account  of  their  great 
abundance.  For  this  reason  they  are  classed  together  in  a  special 
group  which  has  received  the  name  protei?i  gi-oup  (from  npoorevoo, 
I  am  the  first  or  take  the  first  place).  The  bodies  belonging  to 
these  several  groups  are  called  protein  suistanves,  although  in  a 
few  cases  the  albuminous  bodies  in  a  special  sense  are  designated 
by  the  same  name. 

The  i&wexal  protein  substances  contain  carion,  hydrogen,  nitro- 
gen, and  oxygen.  They  generally  contain  also  sulphur,  a  few 
phosphorus,  and  a  few  also  iron.  Copper  has  been  found  in  some 
few  cases.  On  heating  the  protein  substances  they  gradually  de- 
compose, producing  inflammable  gases,  ammoniacal  compounds, 
carbon  dioxide,  water,  nitrogenized  bases,  as  well  as  many  other 
bodies,  and  at  the  same  time  they  emit  a  strong  odor  of  burnt  horn 
or  wool.  More  highly  heated  they  leave  a  porous,  shining  mass  of 
carbon,  and  when  this  is  thoroughly  burnt  an  ash  is  obtained  con- 
sisting chiefly  of  calcium  and  magnesium  phosphates.  The  ques- 
tion whether  the  mineral  bodies  left  by  burning  exist  as  impurities 
or  whether  they  are  constituents  of  the  protein  molecule  has  not 
been  decided. 

It  is  at  present  impossible  to  decide  on  a  classification  of  the 
protein  substances  based  upon  their  properties,  reactions,  and  con- 
stitution, as  well  as  upon  their  solubilities  and  precipitations,  corre- 
sponding to  the  demands  of  science.  The  best  classification  is 
perhaps  the  following  systematic  summary  of  the  better  known 

13 


14 


PHT8I0L0GICAL   CHEMISTBY. 


and    studied  animal    protein    substances,  due   mainly   to   Hoppb- 
Setlee  and  Dp.echsel. 


Albumins . 


Globulins . 


I.  Albuminous  Bodies. 

Serum  albumin, 
Ovalbumin, 
L  act  albumin. 

'  8erum  globulin, 

Fibrinogen, 

Myosin, 

Musculin, 

I  Vitellin  (?). 

[  Casein, 

Nucleoalbumins    }   Ovovitellin  (?), 

(  Pyin,  and  others. 

-,,_.,  (  Acid  albuminate, 

Albuminates \     .-,-,-,-    -.n       ■     , 

(  Alkali  albuminate. 

Albumoses  and  Peptones. 

j  Fibrin, 

{  Albumin  coagulated  by  heat,  and  others. 


Coagulated . 


Mucine , 


II.  Proteids. 

Pure  Mucin, 
Mucoide  or  Mucinoide. 


(Hyalogen.) 
Haemoglobin. 


*II.  Albumoides  or  Albuminoides. 
Keratine. 
Elastin. 
Collagen. 
(Amyloid.) 

{Fibroin,  Sericin,  Cornein,  Spongin,  Conchiolin,  Byssus,  and 
others.) 

To  this  summary  must  be  added  that  we  often  find  in  the  in- 
vestigations of  animal  fluids  and  tissues  protein  substances  which 


THE  PROTEIN  SUBSTANCES. 


15 


do  not  coincide  with  the  above  scheme  or  do  so  only  with  difficulty. 
At  the  same  time  it  must  be  remarked  that  bodies  will  be  found 
which  seem  to  rank  between  the  different  groups. 


I.  Native  Albumins. 


/(5^ 


The  albuminous  bodies  are  never-failing  constituents  of  the 
animal  and  vegetable  organisms.  They  are  especially  found  in  the 
animal  body,  where  they  form  the  solid  constituents  of  the  muscles, 
glands,  and  the  blood  serum,  and  they  are  so  generally  distributed 
that  there  are  only  a  few  animal  secretions  and  excretions,  such  as 
the  tears,  perspiration,  and_  perhaps  urine,  in  which  they  are  en- 
tirely absent  or  only  occur  as  traces. 

All  albuminous  bodies  contain  carbon,  hydrogen,  nitrogen,  oxy- 
gen, and  sulphur;  a  few  contain  also  phosphorus.  Iron  is  generally 
found  in  traces  in  their  ash,  and  it  seems  to  be  a  regular  constitu- 
ent of  a  certain  group  of  the  albuminous  bodies,  namely,  the 
nucleo-albumin  group.  The  composition  of  the  different  albu- 
minous bodies  deviates  a  little,  but  the  variations  are  within  rela- 
tively close  limits.  For  the  better  studied  animal  albuminous 
bodies  the  following  conposition  of  the  ash-free  substance  has  been 
given: 

C 50.6  —  54.5  per  cent. 

H 6.5  —     7.3 

N 15.0  —  17.6 

S 0.8  —     2.2 

P 0.42  —     0.85 

0 21.50  —  23.50 

A  part  of  the  nitrogen  of  the  albumin  molecule  is  loosely  com- 
bined and  splits  off  easily  as  ammonia  by  the  action  of  alkalies 
(Nasse).  Sulphur  shows  the  same  property  in  nearly  all  albu- 
minous bodies  (Fleitmank,  Danilewskt,  Krugee).  A  part  of 
the  sulphur  separates  as  potassium  or  sodium  sulphide  on  boiling 
with  caustic  potash  or  soda,  and  may  be  detected  by  lead  acetate. 
What  remains  can  only  be  detected  after  fusing  with  nitre  and 
sodium  carbonate  and  testing  for  sulphates.  The  albumin  molecule 
therefore   contains  at  least  2  atoms  of  sulphur.     The  molecular 


16  PHYSIOLOGICAL  CEEMISTRT. 

weight  of  the  albumins  has  not  been  determined,  therefore  it  is 
impossible  to  give  formulae.  For  the  alkali  albuminate,  in  whose 
formation  from  native  albumins  a  part  of  the  nitrogen  and  the 
loosely-bound  sulphur  is  split  off,  Lieberkuhn"  has  given  the 
formula  C„H,„N,,SO,,. 

The  constitution  of  the  albuminous  bodies,  notwithstanding 
numerous  investigations,  is  still  unknown.  By  heating  albumin 
with  barium  hydrate  and  water  in  sealed  tubes  at  150"-200°  C.  for 
several  days,  Schxjtzenberger  obtained  a  number  of  products 
among  which  were  ammonia,  carbon  dioxide,  oxalic  acid,  acetic 
acid,  and,  as  chief  product,  a  mixture  of  amido-acids.  This  mix- 
ture  contained,  besides  a  little  tyrosin  and  a  few  other  bodies, 
chiefly  acids  of  the  series  CnHan+i^Oa  [leucines)  and  CnHgn-iNOg 
(leuceines).  The  sulphur  of  the  albumins  yields  sulphites.  The 
three  bodies,  carbon  dioxide,  oxalic  acid,  and  ammonia,  are  formed 
in  the  same  relative  proportion  as  in  the  decomposition  of  urea 
and  oxamid;  therefore  Schutzenberger  suggests  that  perhaps 
albumin  may  be  considered  as  a  very  complex  ureid  or  oxamid. 
Such  a  conclusion  cannot  be  derived  from  the  above  decomposition 
processes  for  several  reasons,  and  the  attempts  to  prepare  urea 
directly  by  splitting  albumin  by  means  of  trypsin,  or  by  oxidation, 
have  given  negative,  or  at  least  not  positive,  results. 

On  fusing  albumin  with  caustic  alkali,  ammonia  and  other 
volatile  products  are  generated;  among  these  leucin,  from  whicli 
volatile  fatty  acids,  such  as  acetic  acid,  valerianic  acid,  and  also 
butyric  acid,  are  formed ;  also  tyrosin,  from  which  phenol,  indol, 
and  skatol  are  produced.  The  majority  of  these  products  are 
found  as  a  result  of  putrefaction  (see  Chap.  VII).  On  boiling 
with  mineral  acids,  or  still  better  by  boiling  with  hydrochloric 
acid  and  zinc  chloride  (Hlasiwetz  and  Habermajsti^),  the  albumins 
yields  amido-acids,  such  as  leucin,  aspartic  acid,  glutamic  acid,  and 
tyrosin  (and  from  vegetable  albumin  Schulze  and  Barbieri  ob- 
tained «r-j)henylamido-propionic  acid),  also  sulphuretted  hydrogen, 
ammonia,  and  nitrogenized  bases  (Deechsel).  As  an  essential 
difference  between  the  action  of  acids  and  alkalies  (barium  hydrate) 
on  albumins,  Drechsel  suggests  that  by  the  action  of  acids  car- 
bon dioxide,  oxalic  and  acetic  acids  are  not  produced. 

By  the  putrefaction  of  albumins,  as  well  as  by  decomposition 


THE  PROTEIN  SUBSTANCES.  17 

by  means  of  acids  or  alkalies,  and  also  by  certain  enzymes,  among 
other  products  amido-acids  are  produced,  and  these  have  a  certain 
significance  for  the  probable  formation  of  the  albumins.  It  isv 
more  than  likely  that  in  the  synthesis  of  albumin  in  the  plant  ' 
from  the  ammonia  or  the  nitric  acid  of  the  soil,  amido-acids  or  acid 
amids,  among  which  asparagin  plays  an  important  role,  are  pro- 
duced; and  from  these  the  albuminous  bodies  are  derived  by  the 
influence  of  glucose  or  other  non-nitrogenized  combinations. 

By  the  oxidation  of  albumins  in  acid  solutions,  volatile  fatty  acids,  their  alde- 
hydes, nitriles,  ketones,  also  benzoic  acid  are  obtained,  also  hydrocyanic  acid 
by  oxidizing  with  potassium  dichromate  and  acid.  Nitric  acid  gives  various 
nitro-products,  such  as  xanthoproteic  acid  (VAisr  dee  Pants),  trinitroalbumin 
(LoEW)  or  oxynitroalbumin,  uitrobenzoic  acid,  and  others.  With  aqua  regia 
fumaric  acid,  oxalic  acid,  chloruzol,  and  other  bodies  are  produced.  By  the 
action  of  bromine  under  stronger  pressure  a  large  number  of  derivatives  are 
obtained,  such  as  bromanil  and  tribromacetic  acid,  bromoform,  leucin,  leu- 
cinimid,  oxalic  acid,  tribromamido-benzoic  acid,  peptone,  and  bodies  similar 
to  humus. 

By  the  dry  distillation  of  albumins  we  obtain  a  large  number  of  decompo- 
sition products  of  a  disagreeable  burnt  odor,  and  a  porous  glistening  mass  of 
carbon  containing  nitrogen  is  left  as  a  residue.  The  products  of  distillation 
are  partly  an  alkaline  liquid  which  contains  ammonium  carbonate  and  acetate, 
ammonium  sulphide,  ammonium  cyanide,  an  inflammable  oil  and  other  bodies, 
and  a  brown  oil  which  contains  hydrocarbons,  nitrogenized  bases  belonging 
to  the  aniline  and  pyridine  series,  and  a  number  of  unknown  substances. 

It  is  impossible  here  to  discuss  all  the  products  obtained  by  the 
action  of  different  reagents  on  the  albumins,  but  from  the  above- 
described  bodies  from  the  decomposition  of  albumin  it  is  clear  that 
the  products  belong  in  part  to  the  fatty  and  in  part  to  the  aro- 
matic series.  Even  though  the  constitution  of  the  albumins  has 
as  yet  not  been  successfully  demonstrated,  it  seems  to  be  a  fact  from 
the  above  that  in  the  albumin  molecule  we  have,  besides  the  atomic 
arrangement  belouging  to  the  fatty  series,  at  least  one  aromatic 
group  present. 

By  the  oxidation  of  albumin  by  means  of  potassium  permanganate,  Maly 
obtained  an  acid,  the  oxyprotosulphonic  acid,  C  51.21;  H  6.89;  N  14.59;  S 
1.77;  0  25.54,  which  is  not  a  product  of  splitting,  but  an  oxidation  product  in 
which  the  group  SH  is  changed  iuto'SOo.OH.  This  acid  does  not  give  the 
proper  color  reaction  with  Millon's  reagent  (see  below),  nor  does  it  yield  the 
ordinary  aromatic  splitting  products  of  the  albumins.  Still  the  aromatic 
group  is  not  absent,  but  it  seems  to  be  in  another  binding  from  that  in  ordi- 
nary albumin.  On  oxidizing  with  potassium  dichromate  and  acid  this  group 
appears  as  benzoic  acid,  and  on  fusing  with  alkali,  benzol  is  given  off. 

The  animal  albuminous  bodies  are  odorless  and  tasteless,  ordi- 
narily amorphous.     The  crystalloid  (Dotterplattchen)  occurring 


18  PHYSIOLOGIGAL   CHEMISTRY. 

in  the  eggs  of  certain  fishes  and  amphibians  does  not  consist  of 
pure  albumin,  but  of  an  albumin  containing  large  amounts  of 
lecithin  which  seems  to  be  combined  with  mineral  substances. 
Crystalline  combinations  of  albumin  with  mineral  substances  have 
been  prepared  from  seeds  of  various  plants,  and  lately  crystallized 
animal  albumin  in  combination  with  salts  has  been  prepared 
(Hofmeister).  In  the  dry  condition  the  albuminious  bodies  ap- 
pear as  a  white  powder,  or  when  in  thin  layers  as  yellowish,  hard, 
transparent  plates.  A  few  are  soluble  in  water,  others  only  soluble 
in  salty  or  faintly  alkaline,  or  acid  solutions  while  others  are  insol- 
uble in  these  solvents.  All  albuminous  bodies  when  burnt  leave 
an  ash,  and  it  is  therefore  questionable  whether  there  exists  an  al- 
buminous body  which  is  soluble  in  water  without  the  aid  of  mineral 
substances.  Nevertheless  it  has  not  been  thus  far  successfully 
proved  that  a  native  albuminous  body  can  be  prepared  perfectly 
free  from  mineral  substances  without  changing  its  constitution  or 
its  properties.  The  albuminous  bodies  are  in  most  cases  strong 
colloids.  They  diifuse,  if  at  all,  only  very  slightly  through  animal 
membranes  or  parchment-paper,  and  the  albumins  have  generally 
a  very  high  osmotic  equivalent.  All  albuminous  bodies  are  optically 
active  and  turn  the  ray  of  polarized  light  to  the  left. 

On  heating  a  solution  of  albumin  to  the  temperatures  depending 
on  the  albumin  present,  and  with  the  proper  reactions  and  in 
favorable  external  conditions, — as,  for  example,  in  the  presence  of 
neutral  salts, — most  albuminous  bodies  separate  in  the  solid  state  as 
a  crude  or  "  coagulated  "  albumin.  The  different  temperatures  at 
which  the  various  albuminous  bodies  coagulate  in  neutral,  salty 
solutions  give  in  many  cases  a  good  means  for  detecting  and  sepa- 
rating these  bodies. 

The  general  reactions  for  the  albuminous  bodies  are  numerous, 
but  only  the  most  important  will  be  given  here.  To  facilitate  the 
study  of  these  they  have  been  divided  into  the  two  following  groups. 

A.  Precipitation  Reactions  of  the  Albuminous  Bodies. 

^  1.  Coagulation  Test.  An  alkaline  albumin  solution  does  not  co- 
agulate on  boiling,  a  neutral  solution  only  partly  and  incompletely, 
and  the  reaction  must  therefore   be  acid   for  coagulation.     The 


STfl"^  PROTEIN  SUBSTANCES.  19 

neutral  liquid  is  first  boiled  and  then  the  proper  amount  of  acid 
added  carefully.  A  flocculent  precipitate  is  formed,  and  if  prop- 
erly done  the  filtrate  should  be  water-clear.  If  dilute  acetic  acid 
be  used  for  this  test,  the  liquid  must  first  be  boiled  and  then  1,  2, 
or  3  drops  of  acid  added,  depending  on  the  amount  of  albumin 
present,  and  boiled  before  the  addition  of  each  drop.  If  dilute 
nitric  acid  be  used,  then  to  10-15  c.c.  of  the  previously-boiled 
liquid  15-20  drops  of  the  acid  must  be  added.  If  too  little  nitric 
acid  be  added  a  soluble  combination  of  the  acid  and  albumin  is 
formed  which  is  precipitated  by  more  acid.  An  albumin  solution 
containing  a  small  amount  of  salts  must  first  be  treated  with  about 
\ic  NaCl,  since  the  heating  test  may  fail,  especially  on  using  acetic 
^cid,   in    the    presence    of   only   a   slight    amount   of    albumin. 

-jd  2.  Behavior  towards  Mineral  Acids  at  Ordinary    Temperatures. 

The  albumins  are  precipitated  by  the  three  ordinary  mineral  acids 
and  by  metaphosphoric  acid,  but  not  by  orthophosphoric  acid. 
If  nitric  acid  be  placed  in  a  reagent  glass  and  the  albumin  solution 
be  allowed  to  flow  gently  thereon,  a  white,  opaque  ring  of  precipi- 
tated albumin  will  form  where  the  two  liquids  meet  (Heller's 
albumin  test).  3.  Precipitation  by  Metallic  Salts.  Copper  sul- 
phate, neutral  aiid  basic  lead  acetate  (in  small  amounts),  mercuric 
chloride,  and  other  salts  precipitate  albumin.  On  this  is  based  the 
use  of  albumins  as  antidotes  in  poisoning  by  metallic  salts.v>^4.  Pre- 
eipitation  hy  Ferro-  or  Ferricyanide  of  Potassium  in  Acetic  Acid  ' 
Solution.  In  these  tests  the  relative  quantities  of  reagent,  albumin, 
or  acid  do  not  interfere  with  the  delicacy  of  the  test.K  5.  Precipi- 
tation hy  Neutral  Salts,  such  as  Na.SO,  or  NaCl,  when  added  to  s^at- 
u ration  to  the  liquid  acidified  with  acetic  acid  or  hydrochloric  acid. 

^c.  6.  Precipitation  hy  Alcohol.  The  solution  must  not  be  alkaline,  — 
but  must  be  either  neutral  or  faintly  acid.  It  must,  at  the  same 
time,  contain  a  sufficient  quantity  of  neutral  salts. y^T.  Precipita- 
tion hy  Tannic  Acid  in  acetic-acid  solutions.  The  absence  of  neu- 
tral salts  or  the  presence  of  free  mineral  acids  may  not  cause  the 
precipitate  to  appear,  but  after  the  addition  of  a  sufficient  quan- 
tity of  sodium  acetate  the  precipitate  will  in  both  cases  appear. 
8.  Precipitation  hy  Phospho-tungstic  or  Phospho-molyhdic  Acids  in  . — 
the  presence  of  free  mineral  acids.  Potassium-mercuric  iodide  and 
potassium-bismuth  iodide   precipitate  albumin  solutions  acidified 


20  PHYSIOLOGICAL  CEEMISTRT. 

with  hydrochloric  acid.-f-9.  Precipitation  by  Picric  Aoid  in  solu- 
tions acidified  by  organic  acids. 

B.  Color  Eeactions  for  Albuminous  Bodies. 

.  1.  Milton's  reaction.^     A  solution  of  mercuric  nitrate  in  nitric 

acid  containing  some  nitrous  acid  gives  a  precipitate  in  albumin 
solutions  which  at  the  ordinary  temperature  is  slowly,  but  at  the 
boiling-point  more  quickly,  colored  red ;  and  the  solution  may  also  be 
colored  a  feeble  or  bright  red,  depending  on  the  amount  of  albumin. 
Solid  albuminous  bodies,  when  treated  by  this  reagent,  give  the  same 
coloration.  This  reaction,  which  depends  on  the  presence  of  the 
aromatic  group  in  the  albumin,  is  also  given  by  tyrosin  and  other 
benzol  derivatives  with  a  hydroxyl  group  in  the  benzol  nucleus. 

3  2.  Xanthoproteic  reaction.  With  strong  nitric  acid  the  albuminous 
bodies  give,  on  heating  to  boiling,  yellow  flakes  or  a  yellow  solution. 
After  saturating  with  ammonia  or  alkalies  the  color  becomes  orange- 
yellow.  3.  Admnhiewicz'  reactioti.  If  a  little  albumin  is  added  to 
a  mixture  of  1  vol.  concentrated  sulphuric  acid  and  2  vols,  glacial 
acetic  acid  a  reddish-violet  color  is  obtained  slowly  at  ordinary 
temperatures,  but  more  quickly  on  heating.    Gelatine  does  not  give 

7^  this  reaction.  4.  Biuret  test.  If  an  albumin  solution  be  first 
treated  with  caustic  potash  or  soda  and  then  a  dilute  copper 
sulphate  solution  be  added  drop  by  drop,  first  a  reddish,  then  a. 
reddish-violet,  and,  lastly,  a  violet-blue  color  is  obtained.  5.  Al- 
bumin is  soluble  on  heating  with  concentrated  hydrochloric  acid, 
producing  a  violet  color,  and  when  the  albumin  is  first  boiled  with 
alcohol  and  then  washed  with  ether  (Liebermann)  it  gives  a 
beautiful  blue  solution.  6.  With  concentrated  sulphuric  acid  and 
sugar  (in  small  quantities)  the  albuminous  bodies  give  a  beautiful 
red  coloration.  These  color  reactions  apply  to  all  albuminous 
bodies. 

The  delicacy  of  the  same  albumin  reagent  differs  for  the  differ- 

'  The  reagent  is  obtained  in  the  following  way  :  1  pt.  mercury  is  dissolved 
in  2  pts.  of  nitric  acid  (of  sp.  gr.  1.42),  first  when  cold  and  later  by  warming. 
After  complete  solution  of  the  mercury,  add  1  volume  of  the  solution  to  U 
volumes  of  water.  Allow  this  to  stand  a  few  hours  and  decant  tlie  super 
natant  liquid. 


TUE  PROTEIN  SUBSTANCES.  21 

ent  albuminous  bodies,  and  it  is,  on  this  account,  impossible  to  give 
the  degree  of  delicacy  for  each  reaction  for  all  albuminous  bodies. 
Of  the  precipitation  reactions  Heller's  test  (if  we  eliminate  the 
peptones  and  certain  albumoses)  is  recommended  in  the  first  place 
for  its  delicacy,  though  it  is  not  the  most  delicate  reaction,  and 
because  it  can  be  performed  so  easily.  Among  the  precipitation 
reactions,  that  with  basic  lead  acetate  (when  carefully  and  exactly 
executed)  and  the  reactions  6,  7,  8,  and  9  are  the  most  delicate. 
The  color  reactions  1  to  4  show  a  great  delicacy  in  the  order  in 
which  they  are  given. 

No  albumin  reaction  is  in  itself  characteristic^  and,  therefore,  in 
testing  for  albumin  one  reaction  is  not  sufficient,  but  a  number  of 
precipitation  and  color  reactions  must  be  employed. 

For  the  quantitative  estimation  of  coagnlable  albumin  the 
determination  by  boiling  with  acetic  acid  can  be  performed  with 
advantage  since,  by  operating  carefully,  it  gives  exact  results.  The 
precipitation  by  means  of  alcohol  in  the  liquid  which  has  first  been 
neutralized  may  also  be  used  for  this  purpose.  The  alcohol  must 
be  added  so  that  the  liquid  contains  70  to  80  vols,  per  cent.  In 
both  cases  small  amounts  of  albumin  may  remain  in  the  filtrate. 
This  last  may  be  determined  by  concentrating  the  filtrate  sufficiently 
(in  the  alcohol  method  all  the  alcohol  must  be  expelled),  and  remov- 
ing any  separated  fat  by  shaking  with  ether,  and  then  precipitating 
with  tannic  acid,  with  the  addition  of  NaCl  if  necessary.  Ap- 
proximately 63^  of  the  tannic  acid  precipitate  washed  with  cold 
water  and  dried  may  be~  considered  as  albumen.  The  precipi- 
tation by  means  of  copper  sulphate  may  also  be  employed  as  a 
quantitative  method,  while  the  Biuret  reaction  may  be  used  for  the 
quantitative  calorimetric  estimation  of  peptones  and  albumoses. 
The  quantitative  estimation  of  albumin  by  means  of  the  polari- 
scope  is  not  applicable  in  all  cases  and  does  not  give  sufficiently 
exact  results. 

The  separation  of  albumins  from  a  solution  may,  in  most  cases, 
be  performed  by  boiling  with  acetic  acid.  Small  amounts  of  albu- 
min which  remain  m  the  filtrates  may  be  separated  by  boiling  with 
freshly-precipitated  lead  carbonate  (Hofmeister)  or  with  ferric 
acetate  (Hoppe-Setler),  as  described  in  Chapter  XIV  on  the 
urine.  If  the  liquid  cannot  be  boiled,  the  albumin  may  be  pre- 
cipitated by  neutral  salts  and  acid,  or  by  the  very  careful  addition 
of  lead  acetate,  or  by  the  addition  of  alcohol.  If  the  liquid  con- 
tains substances  which  are  precipitated  by  alcohol,  such  as  glycogen, 
then  the  albumin  may  be  separated  by  the  alternate  addition  of 
potassium-mercuric  iodide  and  hydrochloric  acid  (Brucke). 


22  PHYSIOLOOIGAL  CHEMISTRY. 

Synopsis  oi  the  Most  Important  Properties  of  the  Different  Chief 
Groups  of  Albuminous  Bodies. 

Albumins.  These  bodies  are  insoluble  in  water  and  are  not 
precipitated  by  the  addition  of  a  little  acid  or  alkali.  They  are 
precipitated  by  the  addition  of  large  quantities  of  mineral  acids  or 
metallic  salts.  Their  solution  in  water  coagulates  on  boiling  in  the 
presence  of  neutral  salts,  but  a  weak  saline  solution  does  not.  If 
NaCl  or  MgSO^  is  added  to  saturation  to  a  neutral  solution  in 
water  at  a  normal  temperature  or  at  +  30°  C.  no  precipitate  is 
formed ;  but  if  acetic  acid  is  added  to  this  saturated  solution  the 
albumin  readily  separates.  When  ammonium  sulphate  is  added 
in  substance  to  saturation  to  an  albumin  solution  a  complete  pre- 
cipitation occurs  at  ordinary  temperature.  Of  all  the  albuminous 
bodies  the  albumins  are  the  richest  in  sulphur,  containing  from  1.6 
to  2.2fc. 

Globulins.  These  albuminous  bodies  are  insoluble  in  water, 
but  dissolve  in  dilute  neutral  salt  solutions.  The  globulins  are 
precipitated  unchanged  from  these  solutions  by  sufficient  dilution, 
with  water;  and  on  heating  they  coagulate.  The  globulins  dis- 
solve in  water  on  the  addition  of  very  little  acid  or  alkali,  and  on. 
neutralizing  the  solvent  they  reprecipitate. 

The  solution  in  a  minimum  amount  of  alkali  is  precipitated  by 
carbon  dioxide,  but  the  precipitate  may  be  redissolved  by  an  excess 
of  the  precipitant.  The  neutral  solutions  of  the  globulins  contain- 
ing salts  are  partly  or  completely  precipitated  on  saturation  .with 
NaOl  or  MgSO^  in  substance  at  normal  temperatures.  The  globu- 
lins contain  an  average  amount  of  sulphur,  not  below  Ifo. 

A  sharp  line  between  the  globulins  on  one  side  and  the  artificial  albu- 
minates on  the  other  can  hardly  be  drawn.  The  albuminates  are,  indeed, 
as  a  rule  insoluble  in  dilute  common-salt  solutions ;  but  an  albuminate  may 
be  prepared  by  the  action  of  strong  alkali  which  is  soluble  in  common-salt 
solutions  immediately  after  precipitation.  We  also  have  globulins  which  are 
insoluble  in  NaCl  after  having  been  in  contact  with  water  for  some  time. 

—  Nucleoalbumins.  These  bodies  are  found  widely  diffused  in 
both  the  animal  and  vegetable  kingdoms.  They  form  one  of  the 
chief  constituents  of  protoplasm,  while  the  albumins  and  in  part 
also  the   globulins   are  special  constituents  of  the  animal  juices. 


THE  PROTEIN  SUBSTANCES.  23 

The  nucleoalbumins  are  found  in  organs  abound iiTg  in  cells,  but 
they  also  occur  in  secretions  and  sometimes  in  other  fluids  in  aj^pa- 
rent  solution  as  destroyed  and  altered  protoplasm.  The  nucleo- 
albumins behave  like  rather  strong  acids;  they  are  nearly  insoluble 
in  water,  but  dissolve  easily  with  the  aid  of  a  little  alkali.  Such  a 
solution,  neutral  or,  indeed,  a  faintly  acid  one,  does  not  coagulate 
on  boiling.  The  nucleoalbumins  resemble  the  globulins  and  the 
albuminates  in  solubility  and  precipitation  properties,  but  differ  from 
them  in  being  hardly  soluble  in  neutral  salts.  The  most  important 
difference  between  the  nucleoalbumins,  the  globulins,  and  the  albu- 
minates is  that  the  nucleoalbumins  contain  phosphorus,  and  by  the 
action  of  pepsin  hydrochloric  acid  on  nucleoalbumins  a  phosphor- 
ized  product,  nucleiu,  is  split  off  which,  according  to  Liebek- 
MANN,  is  a  combination  of  albumin  with  metaphosphoric  acid. 
The  nucleoalbumins  seem  habitually  to  contain  less  sulphur  than 
the  bodies  of  the  preceding  groups.  Some  iron  is  found  as  a  con- 
stant constituent. 

Alkali  and  Acid  Albuminates.  By  the  action  of  alkalies  all 
native  albuminous  bodies  are  converted,  with  the  elimination  of 
nitrogen  or  by  the  action  of  stronger  alkali  with  the  emission  of 
sulphur,  into  a  new  modification,  called  alkali  albuminate,  whose 
specific  rotation  is  increased  at  the  same  time.  If  caustic  alkali  in 
substance  or  in  strong  solution  be  allowed  to  act  on  a  concentrated 
albumin  solution,  such  as  blood-serum  or  egg-albumin,  the  alkali 
albuminate  may  be  obtained  as  a  solid  which  dissolves  in  water  on 
heating  forming  a  Jelly,  and  which  is  called  "Lieberkuhn's  solid 
alkali  albuminate."  By  the  action  of  dilute  caustic  alkali  solutions 
on  dilute  albumin  solutions  we  have  alkali  albuminates,  formed  slowly 
at  the  ordinary  temperature,  but  more  rapidly  on  heating.  These 
solutions  may  be  modified  by  the  source  of  the  albumin  acted 
upon,  and  also  by  the  extent  of  the  action  of  the  alkali,  but  it  is 
still  always  the  same  reaction. 

If  albumin  is  dissolved  in  an  excess  of  concentrated  hydro- 
chloric acid,  or  if  we  digest  an  albumin  solution  acidified  with  1-2 
p.  m.  hydrochloric  acid  in  the  warmth,  or  digest  the  albumin  alone 
with  pepsin  hydrochloric  acid,  we  obtain  a  new  modification  of 
albumin  which  indeed  may  show  somewhat  varying  properties, 
but  has  also  certain  reactions  in  common  with  ordinary  albumin. 


24  PHYSIOLOGICAL   CHEMISTRY. 

These  modifications,  which  may  be  obtained  in  a  solid  gelatinous 
condition  by  sufficient  concentration,  are  called  acid  albuminates 
or  acid  albumin,  sometimes  also  S5mtonin,  though  we  prefer  to  call 
that  acid  albuminate  syntonin  which  is  obtained  by  extracting 
muscles  with  hydrochloric  acid  of  1  p.  m. 

The  alkali  and  acid  albuminates  have  the  following  reactions  in 
common :  They  are  nearly  insoluble  in  water  and  dilute  common- 
salt  solutions  (see  previous  page),  but  they  dissolve  easily  in  water 
after  the  addition  of  a  very  small  quantity  of  acid  or  alkali.  Such 
a  solution  or  one  nearly  neutral  does  not  coagulate  on  boiling,  but 
is  precipitated  at  the  normal  temperature  on  neutralizing  the  sol- 
vent by  an  alkali  or  an  acid.  A  solution  of  an  alkali  or  acid  albu- 
minate in  acid  is  easily  precipitated  on  saturating  with  JSTaCl,  but 
a  solution  in  alkali  is  precipitated  with  difficulty  or  not  at  all, 
according  to  the  amount  of  alkali  it  contains.  The  nearly  neutral 
solutions  are  precipitated  by  mineral  acids  in  excess,  also  by  many 
metallic  salts. 

Notwithstanding  this  agreement  in  the  reactions,  the  acid  and 
alkali  albuminates  are  essentially  different,  and  by  dissolving  an 
alkali  albuminate  in  some  acid  no  acid  albuminate  solution  is 
obtained,  nor  is  an  alkali  albuminate  formed  on  dissolving  an  acid 
albuminate  in  water  by  the  aid  of  a  little  alkali.  The  alkali 
albuminates  are  relatively  strong  acids.  They  may  be  dissolved  in 
water  with  the  addition  of  CaCOj,  with  the  elimination  of  CO,, 
which  does  not  occur  with  typical  acid  albuminates,  and  they 
show  in  opposition  to  the  acid  albuminates  also  other  variations 
which  stand  in  connection  with  their  strongly-marked  acid  nature. 
Dilute  solutions  of  alkalies  act  more  energetically  on  albumin  than 
do  acids  of  the  same  concentration.  In  the  first  case  a  part  of  the 
nitrogen,  and  often  also  the  sulphur,  is  split  off,  and  from  this 
property  we  may  obtain  an  alkali  albuminate  by  the  action  of  an 
alkali  upon  an  acid  albuminate;  but  we  cannot  obtain  an  acid 
albuminate  by  the  reverse  reaction.     (K.  Mor:n"EE.) 

The  preparation  of  the  albuminates  has  been  given  above.  By 
the  action  of  alkalies  or  acids  upon  an  albumin  solution  the  corre- 
sponding albuminate  may  be  precipitated  by  neutralizing  with  acid 
or  alkali.  The  washed  precipitate  is  dissolved  in  water  by  the  aid 
of  a  little  alkali  or  acid,  and  again  precipitated  by  neutralizing  the 


THE  PROTEIN  SUBSTANCES.  25 

solvent.  If  this  precipitate  which  has  been  washed  in  water  is 
treated  with  alcohol  and  ether,  the  albuminate  will  be  obtained  in  a 
pure  form. 

Albumoses  and  Peptones.  Peptones  are  designated  as  the  final 
products  of  the  decomposition  of  albuminous  bodies  by  means  of 
proteolytic  enzymes,  in  so  far  as  these  final  products  are  still  true 
albuminous  bodies,  while  we  designate  as  albumoses  or  propeptones 
the  intermediate  products  produced  in  the  peptonization  of  albu- 
mins in  so  far  as  they  are  substances  not  similar  to  albuminates. 

Albumoses  and  peptones  may  also  be  produced  by  the  hydro- 
lytic  decomposition  of  the  albumins  with  acids  or  alkalies,  also  by 
the  putrefaction  of  the  same.  They  may  also  be  formed  in  very 
small  quantities  as  by-products  in  the  investigations  of  animal 
fluids  and  tissues,  and  the  question  to  what  extent  these  exist  pre- 
formed under  physiological  conditions  requires  very  careful  inves- 
tigation. 

Between  the  peptones  which  represent  the  last  splitting  prod- 
ucts and  those  albumoses  which  stand  closest  to  the  original 
albumin  we  have  undoubtedly  a  series  of  intermediate  products. 
Under  such  circumstances  it  is  a  difficult  problem  to  try  to  draw  a 
sharp  line  between  the  peptone  and  the  albumose  group,  and  it  is 
just  as  difficult  to  define  our  conception  of  peptones  and  albumoses 
in  an  exact  and  satisfactory  manner. 

The  albumoses  have  been  considered  as  those  albuminous  bodies 
whose  solutions  do  not  coagulate  on  boiling  and  which,  to  dis- 
tinguish them  from  peptones,  were  characterized  chiefly  by  the 
following  properties.  The  watery  solutions  are  precipitated  at  the 
ordinary  temperature  by  nitric  acid  as  well  as  by  acetic  acid  and 
potassium  ferrocyanide,  and  this  precipitate  has  the  peculiarity  of 
disappearing  on  heating  and  reappearing  on  cooling.  If  a  solution 
of  albumoses  is  saturated  with  NaCl  in  substance,  the  albumoses 
are  partly  precipitated  in  neutral  solutions,  but  on  the  addition  of 
acid  saturated  with  the  salt  they  completely  precipitate.  This  pre- 
cipitate, which  dissolves  on  warming,  is  a  combination  of  albumose 
with  the  acid. 

We  formerly  designated  2l^  peptone  that  albuminous  body  which 
was  readily  soluble  in  water  and  which  did  not  coagulate  by  heat, 
whose  solutions  were  precipitated  neither  by  nitric  acid,  nor  by 


26  PHYSIOLOGICAL   CHEMISTRY. 

acetic  acid  and  potassium  ferrocyanide,  nor  by  neutral  salts  and 
acid. 

The  reactions  and  properties  which  the  albumoses  and  peptones 
had  in  common  were  formerly  considered  as  the  following:  They 
give  all  the  color  reactions  of  the  albumins,  but  with  the  biuret  test 
they  give  a  more  beautiful  red  color  than  the  ordinary  albumin. 
They  are  precipitated  by  ammoniacal  lead  acetate,  by  mercuric 
chloride,  alcohol,  tannic,  phospho-tungstic,  phospho-molybdic  acids, 
potassium-mercuric  iodide  and  hydrochloric  acid,  and  lastly  by 
picric  acid.  The  albumoses  and  peptones  have  also  a  greater 
diffusive  power  than  native  albuminous  bodies,  and  the  diffusive 
power  is  greater  the  nearer  the  questionable  substance  stands  to 
the  final  product,  the  so-called  pure  peptone. 

These  old  views  have  undergone  an  essential  change  in  the  last 
few  years.  After  Heyistsius'  observation  that  ammonium  sulphate 
was  a  general  precipitant  for  albumin,  also  peptone  in  the  old 
sense,  Kuhne  and  his  pupils  proposed  this  salt  as  a  means  of  sepa- 
rating albumoses  and  peptones.  Those  products  of  digestion  which 
separate  on  saturating  their  solution  with  ammonium  sulphate  are 
considered  by  Kuhnb  and  indeed  by  most  of  the  modern  investi- 
gators as  albumoses,  while  those  which  remain  in  solution  are  called 
peptones  or  pure  peptone.  This  pure  peptone  is  formed  in  rela- 
tively large  amounts  in  the  pancreatic  digestion,  while  in  the  pepsin 
digestion  it  is  only  small  in  quantity  unless  after  prolonged  diges- 
tion. 

According  to  ScHiJTZENBEKGEE  and  Kuhnb  the  albumins  yield 
two  chief  groups  of  new  albuminous  bodies  when  decomposed  by 
dilute  acids  or  with  proteolytic  enzymes;  of  these  the  anti  group 
shows  a  greater  resistance  to  further  action  of  the  acid  and  enzyme 
than  the  other,  namely,  the  Jiemi  group.  Corresponding  to  these 
views  KiJHNE  divides  the  albumoses  into  two  chief  groups,  the 
antialhumoses  and  hemialhumoses,  and  the  peptones  into  two  chief 
groups,  the  antipeptones  and  the  liemipeptones.  In  the  pepsin 
digestion  we  obtain,  besides  different  albumoses,  a  mixture  of  anti- 
and  hemipeptone,  which  mixture  Kuhne  called  ampJiopeptone. 
In  the  digestion  with  trypsin  (the  proteolytic  enzyme  of  the  pan- 
creas) the  hemipeptone  is  further  split  into  leucin,  tyrosin,  and 
other  substances,  while  the  antipeptone  remains  unchanged.     Only 


THE  PROTEIN  SUBSTANCES.  27 

by  the  sufficiently  energetic  action  of  trypsin  is  one  peptone  at  last 
obtained,  the  so-called  antipeptoue. 

KiJHNE  and  his  pupils,  who  have  conducted  these  complete 
investigations  on  the  albumoses  and  peptones,  classify  the  different 
kinds  of  albumoses  according  to  their  different  solubilities  and  pre- 
cipitation powers.  In  the  pepsin  digestion  of  fibrin  they  obtained 
the  following  albumoses:  1.  Dysalbumose,  which  is  insoluble  in 
water  and  dilute  salt  solutions.  2.  Heteroalhumose,  insoluble  in 
water  but  soluble  in  salt  solution.  3.  Protalhumose,  soluble  in  salt 
solution  and  water.  These  three  albumoses  are  precipitated  by 
NaCl  in  a  neutral  solution,  while  4,  the  D enter oalhumose,  which  is 
soluble  in  salt  solution  or  water,  is  precipitated  (partly)  on  saturat- 
ing with  NaCl,  but  only  after  the  addition  of  an  acid.  This  pre- 
cipitate is  a  combination  of  albumose  and  acid  (Herth). 

Herth  claims  that  the  relative  proportion  of  acid  or  alkaki, 
salt,  water,  or  albumose  in  a  solution  essentially  changes  the  solu- 
bility and  precipitation  power  of  the  same.  He  also  claims  that 
the  occurrence  of  several  different  kinds  of  albumoses  cannot  be 
demonstrated,  because  with  one  and  the  same  albumose,  the  above 
conditions  being  changed,  its  solubilities  and  precipitating  powers 
are  changed.  Hamburger  found  the  same  to  be  true  from  his 
investigations. 

The  albumoses  obtained  from  different  albuminous  bodies  do  not  seem  to 
be  identical.  The  globulinalbumoses  of  Kuhne  and  Chittenden  are  called 
globuloses,  the  vitelliu  albumoses  of  Neumeistek  vitelloses,  those  of  casein 
caseoses  (Chittenden),  those  of  myosin  myosinoses  (Kvrm'E  and  Chittenden), 
and  so  on.  The  different  kinds  of  albumoses  are  distinguished  as  proto,- 
hetero-,  and  (Zetftero-caseoses,  etc. 

Neumeistek  designates  as  atmidalbumose  that  body  which  is  obtained  by 
the  action  of  superheated  steam  on  fibrin.  At  the  same  time  he  also  obtained 
a  substance  called  atmidalbumin  which  stands  between  the  albuminates  and 
the  albumoses. 

Of  the  soluble  albumoses  Netjmeister  designates  protoalbumose 
and  heteroalhumose  as  primari/  albumoses,  while  the  deuteroalbu- 
mose,  which  is  nearly  related  to  the  peptones,  he  calls  secondary 
albumose.  As  essential  difference  between  the  primary  and  sec- 
ondary albumoses  he  suggests  the  following:  The  secondary  albu- 
moses are  not  precipitated  by  nitric  acid  in  liquids  free  from  salt, 
nor  by  copper  sulphate  solution  (2  parts  in  100),  nor  by  NaCl  in 
substance  in  a  neutral  liquid.     Pure  true  peptones  are  not  precipi  • 


28  PHYSIOLOGICAL  CHEMISTRY. 

tated  either  by  picric  acid  or  by  potassium-mercuric  iodide  and 
acid.  The  primary  albumoses  are  completely  precipitated  by 
phospho-molybdic  or  phospho-tungstic  acid,  while  the  secondary 
are  not  quite  completely  precipitated,  and  the  true  peptones  very 
incompletely.  The  peptones  are  also  precipitated  by  mercuric 
chloride  in  neutral  solutions,  and  also  by  tannic  acid  in  liquids  con- 
taining acetic  acid.  This  precipitate  may  be  dissolved  in  an  excess 
of  tannic  acid  (Sebelien). 

The  study  of  the  albumoses  and  peptones,  as  above  indicated, 
has  undergone  in  the  last  few' years  an  essential  transformation. 
It  may  still  be  doubtful  whether  the  behavior  of  a  single  salt,  the 
ammonium  sulphate,  yields  sufficient  basis  for  the  characterization 
of  two  groups  of  albuminous  bodies,  the  albumoses  and  peptones; 
and  this  question  is  warranted  since,  according  to  Neumeistee,  we 
have  a  deuteroalbumose  (found  in  the  pepsin  digestion)  which  is 
not  completely  precipitated  by  ammonium  sulphate.  It  seems  that 
the  transformation  of  albumins  into  peptones  takes  place  through  a 
number  of  intermediate  steps  such  as  starch  undergoes  in  passing 
from  dextrine  into  glucose.  A  complete  separation  of  these  several 
intermediate  products,  as  well  as  their  purification,  is  an  extremely 
difficult  task. 

What  relationship  do  the  albumoses  and  peptones  bear  to  the 
albumin  from  which  they  are  formed  ?  Heeth  has  found  that 
fibrin  albumose  and  fibrin  have  a  similar  constitution.  KiJHNE 
and  Chitttenden,  as  also  CniTTEJSTDEisr  and  his  pupils,  have  ana- 
lyzed the  different  albumoses  from  fibrin,  globulin,  egg-albumin, 
myosin,  and  casein,  and  found  in  a  few  albumoses  an  increase 
and  in  others  a  decrease  in  the  amount  of  carbon,  nitrogen,  and 
sulphur  as  compared  with  the  mother- albumin.  From  the  results 
of  their  analyses  it  has  been  found  that,  with  the  probable  excep- 
tion of  the  peptone  standing  closest  to  the  albumoses,  the  difference 
in  the  constitution  of  the  original  albumins  and  the  corresponding 
albumose  is  sometimes  in  one  direction  and  sometimes  in  another, 
and  is  unessential. 

According  to  the  analyses  of  peptones  (in  the  old  sense)  made 
by  Malt,  Heeth,  and  Henningee,  they  seem  to  have  the  same 
constitution  as  the  albumin.  According  to  the  analyses  by  KtJhne 
and  Chittekden  of  "true"  fibrin  peptone,  part  amphopeptone 


THE  PROTEIN  SUBSTANCES.  29 

and  part  antipeptone  prepared  by  pancreas  infusion,  this  peptone 
was  found  to  contain  about  the  same  amount  of  hydrogen  and  the 
same  or  a  greater  amount  of  nitrogen,  but  less  carbon  than  the  albu- 
moses.  In  his  investigations  on  casein  Chittenden  found,  on  the 
other  hand,  that  in  antipeptone  the  amount  of  carbon  was  higher 
than  in  certain  caseoses.  As  the  preparation  of  true  peptones  in 
a  pure  condition  is  accompanied  with  great  difficulty,  and  as  the 
peptones  (in  the  modern  sense)  analyzed  have  not  always  behaved 
as  true  peptones  towards  the  peptone  reagents  as  described  by 
Neumeister,  it  is  most  difficult  to  draw  any  positive  conclusion 
from  these  analyses.  It  seems,  nevertheless,  that  generally  the 
so-called  true  peptones  are  perhaps  somewhat  poorer  in  carbon  than 
the  corresponding  albumins. 

The  elementary  analyses  made  up  to  the  present  time  have  not 
given  us  a  positive  answer  in  regard  to  the  relationship  existing 
between  the  albumins  on  one  side  and  the  albumoses  and  peptones 
on  the  other.  The  view  that  the  peptone  formation  is  a  hydrolytic 
splitting  is  accepted  by  Hoppe-Setler,  KiJHXE,  Henninger,  and 
indeed  by  recent  investigators.  In  support  of  this  view  we  have 
the  observations  of  Hexnixger  and  HoFiiEiSTER,  according  to 
which  peptones  are  converted  into  an  albumin  similar  to  albu- 
minates by  the  action  of  acetic  acid  anhydride,  or  by  heating  so 
that  water  is  expelled.  According  to  other  investigators,  as  Malt, 
Herth,  Loew,  and  others,  the  formation  of  peptone  is  a  depoly- 
merization  of  the  albumins.  A  third  view  is  that  albumins  and 
peptones  are  isomeric  bodies;  while  a  fourth  view  (Griessmayer) 
claims  that  the  albumins  consist  of  micell  groups  which  on  pepto- 
nization are  first  converted  into  micells  and  then  further  into  a 
molecule.  Though  an  ordinary  albumin  solution  contains  micells 
or  micell  bonds,  so  also  a  peptone  solution  contains  an  albumin 
molecule. 

The  preparation  of  different  albumoses  in  a  complete  pure  form 
is  very  troublesome  and  accompanied  with  a  great  many  difficulties. 
For  this  reason  there  will  be  given  here  only  the  general  methods  by 
which  the  different  albumose  precipitates  are  obtained.  If  we  pro- 
ceed from  a  solution  of  fibrin  in  pepsin  hydrochloric  acid,  we  first 
neutralize,  heat  to  boiling,  filter,  concentrate  the  filtrate,  and  satu- 
rate it  vtdth  common  salt  in  substance.     The  precipitate  is  filtered. 


30  PHYSIOLOGICAL   CHEMISTRY. 

washed  with  a  saturated  salt  solution,  and  then  treated  with  a  10 
per  cent  NaCl  solution;  what  remains  is  called  dysalbumose.  The 
filtered  solution  is  repeatedly  and  completely  dialyzed.  A  part 
separates  which  is  heteroalbumin,  while  the  protalbumose  remains 
dissolved  in  the  liquid.  The  above-mentioned  filtrate  which  has 
had  the  primary  albumoses  removed  and  saturated  with  common 
salt  is  treated  with  acetic  acid  which  has  previously  been  saturated 
with  salt.  The  precipitate  consists  of  deuteroalbumose.  The  re- 
sulting filtrate,  from  which  a  new  precipitate  separates  on  satura- 
tion with  ammonium  sulphate,  contains  the  remainder  of  the 
deuteroalbumose  and  a  little  peptone. 

For  the  preparation  of  true  peptone  we  may  use  a  prolonged 
pepsin  digestion,  but  much  quicker  results  are  obtained  by  the 
use  of  the  trypsin  digestion.  The  neutralized  liquid  is  heated 
to  boiling,  filtered,  sufficiently  concentrated,  and  saturated  while 
boiling  hot  with  ammonium  sulphate.  The  albumoses  which  sepa- 
rate are  filtered.  If  any  peptone  is  present  in  the  cold  filtrate,  a 
beautiful  biuret  reaction  is  obtained  by  the  addition  of  very  strong 
caustic  soda  solution  and  a  little  copper  sulphate  solution,  though 
when  the  products  of  pepsin  digestion  are  employed  this  may 
depend  on  nou-precipitated  deuteroalbumose.  The  greater  part  of 
the  ammonium  sulphate  may  be  removed  from  the  filtrate  by  evap- 
oration and  crystallization  or  by  partial  precipitation  by  alcohol. 
What  now  remains  is  separated  by  the  addition  of  barium  hydrate, 
and  lastly  by  barium  carbonate  with  heat.  The  filtrate  is  concen- 
trated and  precipitated  by  alcohol.  In  regard  to  the  more  detailed 
accounts  of  the  proposed  methods  for  the  preparation  of  pure  pep- 
tone and  the  different  albumoses  the  reader  is  referred  to  the  works 
of  KuHJSTE,  Chittenden,  and  Neumeister. 

The  methods  for  the  detection  of  albumoses  and  peptones  in 
fluids  and  tissue  are  not  very  accurate,  and  therefore,  as  they  can- 
not be  given  without  criticism  which  does  not  enter  into  the  scope 
and  plan  of  this  work,  they  will  be  omitted. 

Coagulated  Albuminous  Bodies.  Albumin  may  be  converted  into 
the  coagulated  condition  by  different  means :  by  heating  (see  page 
18),  by  the  action  of  alcohol,  especially  in  the  presence  of  neutral 
salts,  and  in  certain  cases,  as  in  the  conversion  of  fibrinogen  into 
fibrin  (Chapter  IV),  by  the  action  of  an  enzyme.  The  nature  of  the 
processes  which  take  place  during  coagulation  is  unknown.  The 
coagulated  albuminous  bodies  are  insoluble  in  water,  in  neutral 
salt  solutions,  and  in  dilute  acids  or  alkalies,  at  normal  temperature. 
They  are  dissolved  and  converted  into  albuminates  by  the  action  of 
less  dilute  acids  or  alkalies,  especially  on  heating. 


THE  PROTEIN  SUBSTANCES.  31 


II.  Proteid. 


With  this  name,  as  suggested  by  Hoppe-Seyler,  we  designate 
a  class  of  bodies  which  are  more  complex  than  the  albuminous 
bodies  and  which  yield  as  nearest  splitting  products  albuminous 
bodies  on  one  side  and  non-protein  bodies,  such  as  coloring  matters 
and  carbohydrates,  on  the  other. 

The  most  important  substances  belonging  to  this  group  are  the 
blood  -  coloring  matter,  hcemoglohin,  which  will  be  thoroughly 
treated  in  a  following  chapter  (Chapter  IV),  and  mucin  substances 
or  allied  bodies. 

Mucin  Substances.  We  designate  as  mucin  colloid  substances 
whose  solutions  are  mucilaginous  and  thready,  and  which  when 
treated  with  acetic  acid  give  a  precipitate  insoluble  in  an  excess 
of  acid,  and  on  boiling  with  dilute  mineral  acids  yield  a  substance 
capable  of  reducing  copper  oxyhydrate.  This  last-mentioned  fact, 
which  was  first  observed  by  Eichwald,  differentiates  mucin  from 
other  bodies  which  have  long  been  mistaken  for  it  and  which  have 
similar  physical  properties.  On  the  other  hand,  bodies  whose  phy- 
sical properties  differ  from  it  but  which  give  a  reducible  substance 
on  boiling  with  dilute  mineral  acids  have  also  been  designated  as 
mucin. 

The  different  bodies  characterized  as  mucin  substances  cor- 
respond, first,  either  to  true  mucin  or,  second,  to  mucoid  or  mucinoid. 

All  mucin  substances  contain  carbo7i,  liydrogen,  nitrogen, 
sulphur,  and  oxygen.  Compared  with  albuminous  bodies  they 
contain  less  nitrogen  and,  as  a  rule,  less  carbon.  As  close  decom- 
position products  they  yield  albuminous  bodies  on  one  side  and 
carbohydrates  or  acids  related  thereto  on  the  other.  On  boiling 
with  dilute  mineral  acids  they  all  give  a  reducible  substance. 

The  true  mucins  are  characterized  by  their  natural  solution,  or 
one  prepared  by  a  trace  of  alkali,  being  mucilaginous,  thread-like, 
and  giving  a  precipitate  with  acetic  acid  whicli  is  insoluble  in  excess 
of  acid.  The  mucoids  do  not  show  these  physical  properties  and 
have  other  solubilities  and  precipitative  properties.  As  we  have 
intermediate  steps  between  different  albuminous  bodies,  so  also  we 
have  such  between  true  mucins  and  mucoids,  and  a  sharp  line 
between  these  two  groups  cannot  be  drawn. 


32  PHTSIOLOQICAL   CHEMISTRY. 

True  mucins  are  secreted  by  the  larger  mucous  glands,  by  certain 
mucous  membranes,  also  by  the  skin  of  snails  and  other  animals.  True 
mucin  also  occurs  in  the  connective  tissue  and  navel-cord.  Some- 
times, as  in  snails  and  in  the  membrane  of  the  frog-egg  (GtIACOSA), 
a  mother  -  substance  of  mucin,  a  mucinogen,  has  been  found, 
which  may  be  converted  into  mucin  by  alkalies.  Mucoid  substances 
are  found  in  cartilage,  certain  cysts,  etc.  As  the  mucin  question 
has  been  very  little  studied,  it  is  at  the  present  tiiJie  impossible 
to  give  any  positive  statements  in  regard  to  the  occurrence  of 
mucins  and  mucoids,  especially  as  without  doubt  in  many  cases 
non-mucinous  substances  have  been  described  as  mucins.  So  much 
is  sure,  that  mucins  or  nearly-related  bodies  occur  widely  diffused  in 
the  organism  of  certain  tissues.  From  their  decomposition  prod- 
ucts we  derive  a  great  deal  of  knowledge  in  regard  to  the  forma- 
tion and  splitting  of  carbohydrates  or  kindred  bodies  (glycuronic 
acid)  from  other  complex  atoms. 

True  Mucin.  Thus  far  we  have  been  able  to  obtain  only  a  few 
mucins  in  a  pure  and  unchanged  condition  due  to  the  reagents 
used.  The  elementary  analyses  of  these  mucins  have  given  the 
following  results : 

C        H        N        S         O 

Mucin  from  snail 50  32  6.84  13.65  1.75  27,44  (Hammarstew.) 

Mucin  from  nerve 48.30  6.44  11.75  0.81  32.70  (Loebisch.) 

Mucin  from  sub-maxillaris  48.84  6.80  12.32  0.84  31.20  (Hammabsten.) 

The  mucin  of  the  snail-skin,  which  stands  closest  to  keratin, 
contains  more  sulphur  than  the  other  mucins.  The  sulphur  is 
moreover,  at  least  in  certain  mucins,  part  in  loose  and  part  in  strong 
chemical  union. 

By  the  action  of  superheated  steam  on  mucin  a  carbohydrate, 
animal  gum  (Landwehr),  is  split  off.  On  boiling  mucin  with 
dilute  mineral  acids,  acid  albuminate  and  bodies  similar  to  albu- 
mose  or  peptone  are  obtained,  besides  a  reducing  substance  which 
has  not  been  closely  studied.  By  the  action  of  stronger  acids  we 
obtain  among  other  bodies  leucin,  tyrosin,  and  laevulinic  acid 
(Landwehr).  Certain  mucins,  as  the  submaxillaris  mucin,  are 
easily  changed  by  very  dilute  alkalies,  as  lime-water,  while  others, 
such  as  nerve-mucin,  are  not  affected  (Loebisch).    If  a  strong 


THE  PROTEIN  SUBSTANCES.  33 

caustic  alkali  solution,  as  a  5  per  cent  KOH  solution,  is  allowed  to 
act  on  sub-maxillaris  mucin,  we  obtain  alkali  albuminate,  a  body 
similar  to  albumose  and  peptone,  and  one  or  more  substances  of  an 
acid  reaction  and  with  strong  reducing  powers. 

In  one  or  the  other  respect  the  different  mucins  act  somewhat 
differently.  For  example,  the  snail  and  nerve  mucins  are  insoluble 
in  dilute  hydrochloric  acid  of  1-2  p.  m.,  while  the  mucin  of  the 
submaxillary  gland  and  the  navel  cord  are  soluble.  Nerve-mucin 
becomes  flaky  with  acetic  acid,  while  the  other  mucins  are  precipi- 
tated in  more  or  less  fibrous,  tough  masses.  Still  all  the  mucins 
have  certain  reactions  in  common. 

In  the  dry  state  mucin  forms  a  white  or  yellowish-gray  powder. 
When  moist  it  forms,  on  the  contrary,  flakes  or  yellowish-white 
tough  lumps  or  masses.  The  mucins  are  acid  in  reaction.  They 
give  the  color  reactions  of  the  albuminous  bodies.  They  are  not 
soluble  in  water,  but  may  give  a  neutral  solution  with  water  and 
the  smallest  quantity  of  alkali.  Such  a  solution  does  not  coagulate 
on  boiling,  while  acetic  acid  gives  at  the  normal  temperature  a 
precipitate  which  is  insoluble  in  an  excess  of  the  precipitant.  If 
5-10^  NaCl  be  added  to  a  mucin  solution,  this  can  now  be  care- 
fully acidified  with  acetic  acid  without  giving  a  precipitate.  Such 
acidified  solutions  are  copiously  precipitated  by  tannic  acid ;  with 
potassium  ferrocyauide  they  give  no  precipitate,  but  on  sufficient 
concentration  they  become  thick  or  viscous.  A  neutral  solution  of 
mucinalkali  is  precipitated  by  alcohol  in  the  presence  of  neutral 
salts;  they  also  give  precipitates  with  several  metallic  salts.  If 
mucin  is  heated  on  the  water-bath  with  dilute  hydrochloric  acid  of 
about  2^,  the  liquid  gradually  becomes  a  yellowish  or  dark  brown 
and  reduces  copper  oxhydrate  from  alkaline  solutions. 


The  mucin  most  easily  obtained  in  large  quantities  is  the  sub- 
maxillary mucin,  which  may  be  prepared  in  the  following  way: 
The  filtered  watery  extract  of  the  gland,  as  colorless  as  possible,  is 
treated  with  25,^  hydrochloric  acid,  so  that  the  liquid  contains 
1.5  p.  m.  HCl.  On  the  addition  of  the  acid  the  mucin  is  imme-^ 
diately  precipitated,  but  dissolves  on  stirring.  If  this  acid  liquid  Ie 
immediately  diluted  with  2-3  vols,  of  water,  the  mucin  separates 
and  may  be  purified  by  redissolving  in  1-5  p.  m.  acid  and  diluting 
with  water  and  washing  therewith.     The  mucin  of  the  navel-cord 


34  PHYSIOLOGICAL  CHEMISTRT. 

may  be  prepared  in  the  same  way.'  The  nerve  mucin  *.s  prepared 
from  nerves  which  have  first  been  freed  from  albumin  by  common- 
salt  solution  and  water.  They  are  extracted  with  lime-water,  the 
filtrate  is  precipitated  with  acetic  acid,  and  the  precipitate  purified 
by  redissolving  in  dilute  alkali  or  lime-water,  precipitating  with 
acid,  and  washing  with  water  (Kollett,  Loebisch).  Lastly,  the 
mucin  is  treated  with  alcohol. 

2.  Mucoids  or  Mucinoids.  To  this  group  belong  pseudomucin, 
which  occurs  in  ovarial  liquids,  colloid,  which  is  probably  related 
thereto,  and  chondromucoid,  which  occurs  in  cartilage.  These 
bodies  will  be  treated  of  later  in  their  respective  chapters. 

Hyalogen.  Under  this  name  Kruke^stbekg  has  designated  a  number  of 
differing  protein  bodies,  which  are  characterized  by  the  following:  By  the 
action  of  alkalies  they  change,  with  the  splitting  off  of  sulphur  and  nitrogen, 
into  a  soluble  nitrogenized  product  called  by  him  hyaline  and  which  yields  a 
pure  carbohydrate  by  further  decomposition.  Within  this  group  the  most 
widely  differing  substances  may  find  place,  as  for  instance  true  mucin  and 
mucoid,  the  so-called  mucin  of  the  holoihuria,  neossin  of  the  edible  bird'snest, 
the  glycoproteid  of  the  vineyard  snail,  the  onuphin  and  spirographin,  and  other 
substances  from  the  lower  animals.  It  is  of  very  little  value  to  collect  into 
one  group  all  these  differing  substances,  which  have  very  little  in  common, 
until  we  have  learned  with  some  degree  of  certainty  the  nature  of  the  re- 
ducible substances  and  other  products  obtaiued  from  them. 

III.  Albumoids  or  Albuminoids. 

CTnder  this  name  we  collect  into  a  special  group  all  those  pro- 
tein bodies  which  cannot  be  placed  in  either  of  the  other  two 
groups,  although  they  differ  essentially  among  themselves  and  from 
a  chemical  standpoint  do  not  show  any  prevailing  difference  from 
the  ordinary  albuminous  bodies.  The  most  important  and  abun- 
dant of  the  bodies  belonging  to  this  group  are  important  con- 
stituents of  the  animal  skeleton  or  the  animal  structure.  They 
occur  as  a  rule  in  an  insoluble  state  in  the  organism,  and  they  are 
marked  in  most  cases  by  a  great  resistance  to  reagents  which  dis- 
solve albumins  or  to  chemical  reagents  in  general. 

The  Keratin  Group.  Keratin  is  the  chief  constituent  of  the 
horny  structure,  of  the  epidermis,  of  hair,  wool,  of  the  nails,  hoofs, 
horns,  feathers,  of  tortoise-shell,  etc.,  etc.  Keratin  is  also  found  as 
neurokeratin  (Kuhne)  in  the  brain  and  nerves.  The  shell-mem- 
brane of  the  hen's  egg  seems  also  to  contain  keratin. 

'  The  author  has  not  been  able  to  obtain  this  pure,  so  the  analysis  has 
not  been  given  in  the  previous  table  of  the  mucins. 


THE  PROTEIN  SUBSTANCES. 


35 


It  seems  that  there  exist  more  than  one  keratin,  and  these 
varieties  form  a  special  gi-oup  of  bodies.  This  fact,  together  with 
the  difficulty  in  isolating  the  keratin  from  the  tissues  in  a  pure 
condition  without  a  partial  decomposition,  is  sufficient  explanation 
for  the  variation  in  the  elementary  constitution  given  below.  As 
examples  the  analyses  of  a  few  tissues  rich  in  keratin  and  of  kera- 
tin itself  are  given  as  follows : 


Human  hair 

50.65     ' 

6.36 

17.14 

5.00 

20.85 

(v.  Laar.) 

Nail 

51.00 

6.94 

17.51 

2.80 

21.75 

(Mulder.) 

Neurokeratin. .. 

56.11-58.45 

7.26-8.02 

11.46-14.32 

1.63-2.24 

(KCHNE.) 

Horn  (avrt-age) . 

50.86 

6.94 

3.30 

(HORBACZEWSKI.J 

Tortoise-shell. . . 

54.89 

6.56 

16.77 

2.22 

19.56 

(Mulder.) 

Shell-membrajie 

49.78 

6.64 

16.43 

4.25 

20.90 

(LiKDVALL.) 

Sulphur  is  at  least  in  part  in  loose  combination,  and  it  is  partly 
removed  by  the  action  of  alkalies  (as  sulphides),  or  indeed  by  boil- 
ing with  water  (Chevreul).  Combs  of  lead  after  long  usage 
become  black,  and  this  is  due  to  the  action  of  the  sulphur  of  the 
hair.  On  heating  keratin  with  water  in  sealed  tubes  at  a  tempera- 
ture of  150°  to  200°  C.  it  dissolves,  with  the  elimination  of  sulphu- 
retted hydrogen,  forming  a  non-gelatinizing  liquid  which  contains 
albumose  (called  Jceratinose  by  Krukexberg)  and  peptone  (?). 
The  keratin  may  be  dissolved  by  alkalies,  especially  on  heating, 
forming,  besides  alkali  sulphides,  albumoses  and  peptones  (?). 
That  the  keratin  in  the  organism  is  formed  from  the  albumin  is 
not  to  be  denied.  Drechsel  believes  that  in  keratin  a  part  of  the 
oxygen  of  the  albumins  is  exchanged  for  sulphur,  and  a  part  of  the 
leucin  or  any  other  amido-acid  is  exchanged  for  tyrosin.  The 
products  of  decomposition  of  keratin  and  of  albumin  are  similar, 
except  that  the  former  gives  proportionally  a  greater  amount  of 
tjTosin  (3-5$^). 

Keratin  is  amorphous  or  takes  the  form  of  the  tissues  from 
which  it  was  prepared.  On  heating  it  decomposes  and  generates 
an  odor  of  burnt  horn.  It  is  insoluble  in  water,  alcohol,  or  ether. 
On  heating  with  water  to  150°-200°  C.  it  dissolves.  It  also 
dissolves  gi'adually  in  caustic  alkalies,  especially  on  heating.  It  is 
not  dissolved  by  artificial  gastric  juice  or  by  trypsin  solutions. 
Keratin  gives  the  xanthoproteic  acid  reaction,  as  well  as  the  reac- 


iiQ  PHYSIOLOGICAL  CHEMISTRY 

tions  with  Millon's  reagent,  even  though  they  are  not  always 
typical. 

In  the  preparation  of  keratin  a  finely-divided  horny  structure 
is  treated  first  with  boiling  water,  then  consecutively  with  diluted 
acid,  pepsin-hydrochloric  acid,  and  alkaline  trypsin  solution,  and, 
lastly,  with  water,  alcohol,  and  ether. 

Elastin  occurs  in  the  connective  tissue  of  higher  animals,  pome- 
times  in  so  large  quantities  that  it  forms  a  special  tissue.  It  occurs 
most  abundantly  in  the  cervical  ligament  (ligamentum  nuchae). 
It  seems  that  there  is  more  than  one  kind  of  elastin. 

Elastin,  according  to  the  general  view,  is  free  from  sulphur. 
According  to  the  investigations  of  Chittenden  and  Hart,  it  is  a 
question  whether  or  not  elastin  contains  sulphur  which  is  removed 
by  the  action  of  the  alkali  in  its  preparation.  The  most  trust- 
worthy analyses  of  elastin  from  the  cervical  ligament  have  given 
the  following  results : 

C  H  F  O 

54.33  6.99  16.75  2194    (Horbaczewskt.) 

54.24  7.2i  16.70        •   21.79    (Chittenden  and  Hart.) 

As  splitting  products  we  find  leucin,  tyrosin  (in  small  quantity), 
glycocoll,  amido-valerianic  acid,  ammonia,  and  others.  No  indol 
or  phenol  is  obtained  on  putrefaction.  On  heating  with  water  in 
closed  vessels,  on  .boiling  with  dilute  acids,  or  by  the  action  of  a 
proteolytic  enzym,  the  elastin  dissolves  and  splits  into  two  chief 
products,  cahed  by  Horbaczewski  hemielastin  and  elastinpeptone. 
According  to  Chittenden  and  Hart,  these  products  correspond 
to  two  albumoses  designated  by  them  protoelastose  and  deutero- 
elastose.  The  first  is  soluble  in  cold  water  and  separates  on  heating, 
and  its  solution  is  precipitated  by  mineral  acid  as  well  as  by  acetic 
acid  and  potassium  ferrocyanide.  The  watery  solution  of  the  other 
does  not  become  cloudy  on  heating,  and  is  not  precipitated  by  the 
above-mentioned  reagents. 

Pure  dry  elastin  is  a  yellowish- white  powder;  in  the  moist  state 
it  appears  like  yellowish-white  threads  or  membranes.  It  is  insol- 
uble in  water,  alcohol,  or  ether,  and  shows  a  resistance  against  the 
action  of  chemical  reagents.     It  is  not  dissolved  by  strong  caustic 


THE  PROTEIN  SUBSTANCES.  37 

;alkalies  at  the  ordinary  temperature,  and  only  slowly  at  the  boiling 
temperature.  It  is  very  slowly  attacked  by  cold  concentrated  sul- 
phuric acid,  and  it  is  relatively  easily  dissolved  on  warming  with 
strong  nitric  acid.     It  gives  Millon's  reaction. 

On  account  of  its  great  resistance  to  chemical  reagents,  elastin 
may  be  prepared  (best  from  the  ligamentum  nuchas)  in  the  fol- 
lowing way:  First  boil  with  water,  then  with  l<fo  caustic  potash, 
then  again  with  water,  and  lastly  with  acetic  acid.  The  residue 
is  treated  with  cold  5^  hydrochloric  acid  for  twenty-four  hours, 
carefully  washed  with  water,  boiled  again  with  water,  and  then 
treated  with  alcohol  and  ether. 

Collagen,  or  glue-forming  substance,  occurs  very  extensively  in 
the  animal  kingdom,  especially  in  the  vertebrates,  seldom  in  the 
invertebrates.  Collagen  is  the  chief  constituent  of  the  fibres  of 
the  connective  tissue  and  (as  ossein)  of  the  organic  substances  of 
the  bony  structure.  It  also  occurs  in  the  cartilaginous  tissues  as 
chief  constituent,  but  it  is  here  mixed  with  another  substance 
which  was  formerly  called  chondrigen.  Collagen  from  different 
tissues  has  not  quite  the  same  composition,  and  probably  there  are 
several  varieties  of  collagen. 

By  continuously  boiling  with  water  (more  easily  in  the  presence 
of  a  little  acid)  collagen  is  converted  into  gelatine.  Hofmeister 
found  that  gelatine,  on  being  heated  to  130''  C,  is  transformed  into 
collagen;  and  this  last  may  be  considered  as  the  anhydride  of  gela- 
tine.    Collagen  and  gelatine  have  the  following  composition: 

C 

Collagen 50.75 

Gelatine  (from  hartshorn) .     49.31 
Gelatine  (from  bones) 50.00 

The  gelatine  contains  about  0.6^  sulphur,  which  probably  be- 
longs to  the  gelatine  and  hardly  exists  there  as  an  impurity  from 
the  albumin. 

The  investigations  in  regard  to  the  decomposition  products  of 
collagen  have  been  made  on  gelatine.  Gelatine  yields,  under  simi- 
lar conditions  as  albuminous  bodies,  amido-acids,  but  no  tyrosin. 
It  yields  a  large  amount  of  glycocoll,  to  which,  on  this  account,  the 
name  of  glue-sugar  has  been  given.    On  putrefaction  gelatine  gives 


H 

N 

s-i-o 

6.47 

17.86 

24.93 

(HoPMEISTEK.) 

6.55 

18.87 

25.77 

(Mulder.) 

6.50 

17.50 

26.00 

(Fremy.) 

38  PHYSIOLOGICAL   CHEMISTRY. 

neither  tyrosin  nor  indol,  in  which  it  deviates  from  e  albumins,. 
Still  the  aromatic  group  is  not  absent  in  gelatine,  and  it  acts  like 
the  oxidized  albumin,  the  oxyprotsulphonic  acid  giving  benzoic 
acid  (Malt).  On  treating  gelatine  with  hydrochloric  acid  and 
alcohol  and  then  acting  on  this  with  a  nitrite,  Buchner  and  Cue- 
Tius  obtained  an  ester  of  a  diazo-fatty  acid,  probably  diazo-oxyacry- 
lic  acid  ester,  and  it  is  therefore  also  possible  that  the  nucleus  of 
the  gelatine  is  formed  of  amido-acrolein. 

Collagen  is  insoluble  in  water,  salt  solutions,  dilute  acids,  and 
alkalies,  but  it  swells  up  in  dilute  acids.  By  continuous  boiling 
with  water  it  is  converted  into  gelatine.  It  is  dissolved  by  the 
gastric  juice  and  also  by  the  pancreatic  juice  (trypsin  solution) 
when  it  has  previously  been  treated  with  acid  or  heated  with 
water  above  +  70°  C.  By  the  action  of  ferrous  sulphate,  corrosive 
sublimate,  or  tannic  acid,  collagen  shrinks.  Collagen  treated  by 
these  bodies  does  not  putrefy,  and  the  tannic  acid  is  therefore  of 
great  importance  in  the  preparation  of  leather. 

Gelatine  or  glue  is  colorless,  amorphous,  and  transparent  in  thin 
layers.  It  swells  in  cold  water  without  dissolving.  It  dissolves  in 
warm  water,  forming  a  sticky  liquid,  which  solidifies  on  cooling 
when  sufficiently  concentrated.  The  solution  is  Isevogyrate;  a]  at 
-|-  30°  C.  =  —  130°.  Acetic  acid  and  alkalies  diminish  the  specific 
rotary  power.  Gelatine  solutions  on  boiling  are  not  precipitated 
either  by  mineral  acids,  acetic  acid,  alum,  lead  acetate,  or  mineral 
salts  in  general.  A  gelatine  solution  acidified  with  acetic  acid  may 
be  precipitated  by  potassium  ferrocyanide  on  carefully  adding  the 
reagent,  but  on  the  addition  of  too  much  potassium  ferrocyanide 
the  liquid  remains  clear.  Gelatine  solutions  are  precipitated 
by  tannic  acid  in  the  presence  of  salt;  by  acetic  acid  and  common 
salt  in  substance;  mercuric  chloride  in  the  presence  of  H CI  and 
NaCl ;  phosphomolybdic  acid  in  the  presence  of  acid ;  and  lastly  by 
alcohol,  especially  when  neutral  salts  are  present.  Gelatine  solu- 
tions do  not  diffuse.  Gelatine  gives  the  biuret  reaction,  but  not 
Adamkiewicz's.  It  gives  Millon's  reaction  and  the  xanthoproteic 
acid  reaction  so  faintly  that  it  probably  occurs  from  an  impurity 
consisting  of  albumin.  By  continuous  boiling  with  water, — espe- 
cially in  the  presence  of  dilute  acid,^ — also  by  digesting  with  gastric 


THE  PROTEIN  SUBSTANCES.  39 

juice  or  trypsin  solution,  gelatine  loses  the  property  of  gelatin- 
izing and  is  transformed  into  gelatine-peptone. 

According  to  Hofmeister  it  splits  into  two  substances,  semigluUn  and 
JiemicolUn.  The  former  is  insoluble  iu  alcohol  of  70-80^,  and  is  precipitated 
by  platinum  chloride.  The  latter,  which  is  not  precipitated  by  platinum 
chloride,  dissolves  in  alcohol. 

Collagen  may  be  obtained  from  bones  by  extracting  with  hydro- 
chloric acid  (which  dissolves  the  earthy  matters)  and  then  carefully 
removing  the  acid  with  water.  It  may  be  obtained  from  tendons 
treated  with  lime-water  (which  dissolves  the  albumin  and  mucin), 
and  then  thoroughly  washing  with  water.  Gelatine  is  obtained  by 
boiling  collagen  with  water.  The  finest  commercial  gelatine  con- 
tains a  little  albumin,  which  may  be  removed  by  allowing  the  finely- 
divided  gelatine  to  swell  in  cold  water  and  extracting  thoroughly 
with  large  quantities  of  fresh  water.  In  regard  to  the  preparation 
of  gelatine  from  cartilage  see  Chapter  VIII. 

Chondrin  is  only  a  mixture  of  glue  with  the  specific  constituents  of  cartilage 
and  their  transformation  products.  Spongin  forms  the  great  mass  of  the  ordi- 
nary sponge.  It  gives  no  gelatine,  and  on  boiling  with  acids  it  yields  leucin 
and  glycocoll,  but  no  tyrosiu.  Conchiolin  is  found  in  the  shells  of  mussels 
and  snails,  and  also  in  the  egg-sliells  of  these  animals.  It  yields  leucin  but  no 
tyrosin.  Byssus  contains  a  substance,  closely  related  to  conchiolin,  which  is 
soluble  with  difficulty.  Cornein  forms  the  axial  system  of  the  Antipathes  and 
Gorgouia.  It  gives  leucin  and  a  crystallizable  substance,  cornicrystallin  (Kru- 
kenberg).  Fibroin  and  Sericin  are  the  two  chief  constituents  of  raw  silk. 
By  the  action  of  superheated  water  the  sericin  dissolves  and  gelatinizes  on 
cooling  (silk  gelatine),  while  the  more  difficultly  soluble  fibroin  remains  un- 
dissolved in  tlie  shape  of  the  original  fibre.  On  boiling  with  acid  the  fibroin 
yields  alanin  (Weyl),  glycocoll,  and  a  great  deal  (5-8^)  of  tyrosin.  Fibroin  is 
dissolved  in  cold  concentrated  hydrochloric  acid  with  the  expulsion  of  ]  %  ni- 
trogen as  ammonia,  and  it  is  converted  into  another,  nearly-related  substance 
called  sericoin  (Weyl).  Sericin  yields  no  glycocoll  but  leucin  and  a  crystal- 
lizable substance  called  serin.  The  composition  of  the  above-mentioned 
bodies  is  as  follows  : 

C  H  N         S  O 

Conchiolin  (from  snail-eggs)  50.93  6.88  17.86  0.31  24.34  (Krukenberg  ) 

Spongin 46.50  6.30  16.20  0.5  27.50  (Croockewitt.) 

.■ 48.75  6.85  16.40  (Posselt.) 

Cornein 48.96  5.90  16  81  ....  28.33  (Krukenberg.) 

Fibroin 48.23  6.27  18.31  ....  27.19  (Cramer.) 

Sericin 44.33  6.18  18.30  ....  30.20  (Cramer.) 

Amyloid,  so  called  by  Viechow,  is  a  protein  substance  appear- 
ing under  pathological  conditions  in  the  internal  organs,  such  as 
the  spleen,  liver,  and  kidneys,  as  infiltrations ;  and  in  serous  mem- 
branes as  granules  with  concentric  layers.  It  probably  also  occurs 
as  a  constituent  of  a  few  prostate  calculi.     Amyloid  has  not  been 


40  PHTSIOLOQIGAL   CHEMISTRY. 

obtained  pure,  therefore  its  composition  cannot.be  given  with  cer- 
tainty. Fkiedreich  and  Kekule  found  C  53.6;  H  7.0;  N  15.0; 
and  S  +  0  24.4^.  Kuhn"E  and  Kudn^eff  found  1.3^  sulphur. 
Amyloid  is  not  related  to  the  carbohydrates,  and  on  boiling  with 
acids  it  gives  neither  glucose  nor  any  other  reducing  substance. 
On  the  contrary,  it  yields  leucin  and  tyrosin. 

It  is  insoluble  in  water,  alcohol,  ether,  dilute  hydrochloric  acid, 
and  acetic  acid.  It  is  dissolved  in  concentrated  hydrochloric  acid 
or  caustic  alkali,  and  is  converted  into  acid  or  alkali  albuminates 
according  to  the  agents  employed.  According  to  KosTJUEiisr, 
amyloid  is  dissolved  by  the  gastric  juice,  which  is  the  reverse  of  older 
theories.  Amyloid  gives  the  xanthoproteic  acid  reaction  and  the 
reactions  of  Millon"  and  Adamkiewicz.  Its  most  important 
property  is  its  behavior  with  certain  coloring  matters.  It  is  colored 
reddish  brown  or  a  dingy  violet  by  iodine;  a  violet  or  blue  by  iodine 
and  sulphuric  acid ;  red  by  methylaniline  iodide,  especially  on  the 
addition  of  acetic  acid ;  and  red  by  aniline  green. 

Amyloid  is  prepared  by  extracting  the  tissue  with  cold  and 
then  boiling  water,  afterwards  with  alcohol  and  ether.  After  boil- 
ing with  alcohol  containing  hydrochloric  acid  and  digesting  with 
gastric  juice,  that  which  is  insoluble  is  considered  as  amyloid.  As 
the  amyloid  may  be  dissolved  by  the  gastric  juice,  the  utility  of  this 
method  seems  doubtful. 


CHAPTER  III. 

THE  ANIMAL  CELL. 

The  cell  is  the  unit  of  the  manifold,  variable  forms  of  the  organ- 
ism ;  it  forms  the  simplest  physiological  apparatus,  and  as  such  is  the 
seat  of  chemical  processes.  It  is  generally  admitted  that  all  chemi- 
cal processes  of  importance  do  not  take  place  in  the  animal  fluids, 
but  proceed  in  the  cells,  which  may  be  considered  as  the  chemical 
laboratory  of  the  organism.  It  is  also  principally  the  cells  which, 
through  their  greater  or  less  activity,  regulate  or  govern  the  range 
of  the  chemical  processes  and  also  the  intensity  of  the  total  ex- 
change of  material. 

It  is  natural  that  the  chemical  investigation  of  the  animal  cell 
should  in  most  cases  coincide  with  the  study  of  those  tissues  of 
which  it  forms  the  chief  constituent.  Only  in  a  few  cases  can  the 
cells  be  directly,  by  relatively  simple  manipulations,  isolated  in  a 
rather  pure  state  from  the  tissues,  as,  for  example,  in  the  investiga- 
tion of  pus  or  of  tissue  very  rich  in  cells.  But  even  in  these  cases 
the  chemical  investigation  may  not  lead  to  any  positive  results  in 
regard  to  the  constituents  of  the  uninjured  living  cells.  By  the 
process  of  chemical  transformation  new  substances  may  be  formed 
at  the  death  of  the  cell,  and  at  the  same  time  physiological  constitu- 
ents of  the  cell  may  be  destroyed  or  transported  into  the  surrounding 
menstruum  and  therefore  escape  investigation.  For  this  and  other 
reasons  we  possess  only  a  very  limited  knowledge  of  the  constituents 
and  the  constitution  of  the  cell,  especially  of  the  living  one. 

While  young  cells  of  different  origin  in  the  early  period  of  their 
existence  may  show  a  certain  similarity  in  regard  to  their  form  and 
chemical  constitution,  they  may,  on  further  development,  not  only 
take  the  most  varied  forms,  but  may  also  offer  from  a  chemical 
standpoint  the  greatest  diversity.  As  a  description  of  the  con- 
stituents and  the  constitution  of  the  different  cells  occurring  in  the 
animal  organism  is  nearly  equivalent  to  a  demonstration  of  the 
chemical  relations  of  most  animal  tissues,  and  as  this  exposition 

41 


42  PHYSIOLOGICAL  CHEMISTRY. 

will  be  found  in  their  respective  chapters,  we  will  here  only  discuss 
the  chemical  constituents  of  the  young  cells  or  the  cells  in  general. 

We  must  first  differentiate  between  the  protoplasm  and  the 
nucleus. 

The  Protoplasm  of  the  generative  cell  consists  during  life  of  a 
semi-solid  body  contractile  under  certain  conditions,  very  rich  in 
water,  and  the  mass  of  which  consists  mainly  of  albuminous  bodies. 
If  the  cell  be  deprived  of  the  physiological  conditions  of  life,  or  if 
exposed  to  destructive  exterior  influences,  such  as  the  action  of  high 
temperatures,  of  chemical  agents,  or  indeed  of  distilled  water,  the 
protoplasm  dies.  The  albuminous  bodies  which  it  contains  co- 
agulate at  least  partially,  and  other  chemical  changes  are  found  to 
take  place.  The  alkaline  reaction  of  the  living  cell  may  be  converted 
into  an  acid  by  the  appearance  of  paralactic  acid,  and  the  carbohy- 
drate, the  glycogen,  which  habitually  occurs  in  the  young  genera- 
tive cell  may  after  its  death  be  quickly  changed  and  consumed. 

Tlie  albuminous  bodies  of  the  protoplasm  consist,  according  to 
the  general  view,  chiefly  of  globulins,  but  albumins  are  also  found. 
The  occurrence  of  globulins  in  the  animal  as  well  as  in  the  vegetable 
cell  has  been  specially  shown  by  Hoppe-Seylee,  and  according  to 
this  investigator  two  globulin  substances,  vitellin  and  inyosin, 
occur  in  all  protoplasm.  Halliburton  has  lately  closely  studied 
the  albuminous  bodies  of  the  lymphatic  cells,  and  found  two 
globulins  besides  an  albumin  probably  identical  with  serum  albu- 
min (see  Chapter  IV).  Of  the  globulins,  one  which  occurs  only  in 
small  quantities  coagulates  at  the  temperature  of  48-50°  C,  while 
the  other,  which  occurs  in  abundance,  is  coagulated  like  serum 
globulin  by  a  5^  solution  of  MgSO,  at  75°  C.  The  widespread 
occurrence  of  globulins  and  also  of  albumins  in  the  protoplasm  of 
the  animal  cell  has  been  unquestionably  demonstrated,  but  these 
two  groups  of  albuminous  bodies  do  not,  at  least  in  many  cases, 
form  the  chief  mass  of  the  protoplasm.  The  protoplasm  seems  to 
consist  in  great  part  of  very  complex  protein  substances,  the 
proteids  on  one  side  and  the  nucleoalbumins  on  the  other.  Of  all 
these  the  nucleoalbumins  appear  to  be  regular  constituents  of  thB 
protoplasm,  and  they  do  not  only  appear  in  the  pus  cells  or  in  the 
cells  of  the  lymphatic  glands  (Halliburton),  but  also  in  almost  all 
varieties  of  glandular  cells.     The  chief  mass  of  the  albumins  found 


THE  ANIMAL   CELL.  43 

in  the  protoplasm  appear  to  be  phosphorized,  a  condition  which  is 
of  importance  as  showing  the  genetic  connection  between  the  cell 
nucleus  rich  in  phosphorus  and  the  protoplasm. 

The  extent  to  which  the  proteids  occur  in  the  young  generative 
cells  has  not  been  sufficiently  investigated;  nevertheless  these 
substances  occur  habitually  and  in  significant  amounts  in  certain 
epithelium  and  glandular  cells.  Ditficultly  soluble  protein  sub- 
stances are  also  found  in  dead  cells  or  in  organs  rich  in  cells  which 
act  like  coagulated  albuminous  bodies  when  treated  with  the 
ordinary  reagents. 

In  cases  in  which  the  protoplasm  is  surrounded  by  an  outer,  con- 
densed layer  or  a  cell  membrane,  this  envelope  seems  to  consist  of 
albumoid  substances.  In  a  few  cases — and  these,  according  ta 
DoxDERS,  answer  for  the  primary  animal  cell  membrane — these- 
substances  seem  to  be  closely  related  to  elastin ;  in  other  cases,  on 
the  contrary,  they  seem  rather  to  belong  to  the  keratin  group. 
The  chemical  processes  by  which  these  albumoid  substances  are 
formed  from  the  albuminous  bodies  or  proteids  of  the  protoplasm 
are  unknown. 

The  occurrence  of  phosphorized  organic  combinations  in  all 
protoplasm  is  without  doubt  of  the  greatest  importance  for  the 
functional  task,  as  also  for  the  development  of  the  cell.  Of  the 
phosphorized  combinations  in  the  cell  there  are  at  least  two  chief 
groups.  To  one  belongs  lecithin,  and  to  the  other  nuclein,  the 
latter  occurring  partly  in  the  nucleoalbumin,  and  forming  a  part  of 
the  chief  constituents  of  the  cell  nucleus. 

Lecithin.  This  body  is,  according  to  the  investigations  of 
Strecker,  Hustdeshagen,  and  Gilson,  an  ether-like  combination 
of  glycerophosphoric  acid  substituted  by  fatty  acid  radicals,  with 
a  base,  cholin.  Therefore  there  may  be  different  lecithins  accord- 
ing to  the  fatty  acid  contained  in  the  lecithin  molecule.  One  of 
these  —  distearyllecithin  —  has  been  closely  studied  by  Hoppe- 
Setler  and  Diacoxow  : 

C..H,„NPO,  =  HO.(CH,)3KC,H,.0(OH)PO.O.C3H,:  (C,,H3,0J, 

In  agreement  with  this,  if  lecithin  be  boiled  with  baryta-water 
it  yields  fatty  acids,  glycerophosjDhoric  acid,  and  cholin.  It  is  only 
slowly  decomposed  by  dilute  acids.     Besides   small  quantities  of 


44  PHYSIOLOGICAL  CHEMISTRY. 

glyceropliosphoric    acid  (perhaps   also   distearylglycerophosphoric 
acid)  we  have  large  quantities  of  free  phosphoric  acid  split  off. 

Gltcerophosphoeic  acid  {TiO)^VO.O.(j^^{OW)^  is  a  bibasic 
acid,  which  probably  only  occurs  in  the  animal  fluids  and  tissues  - 
as  splitting  product  of  lecithin.  The  cholin,  which  seems  to  be 
identical  with  the  bases  sijstkalin  (in  mustard-seed)  and  amanitik 
(in  agaricus  muscarius),hasthe  formula  HO.N(CH3)3.C3H^.OH  and 
is  therefore  considered  as  trimethylethoxylium  hydrate.  Cholin  ac- 
cording to  Brieger  is  not  identical  with  the  base,  neurik,  prepared 
by  Liebreich  as  a  decomposition  product  from  the  brain,  which  is 
considered  as  trimethylvinylium  hydrate,  HO.N(CH3)3.C5H3.  The 
combination  of  cholin  with  hydrochloric  acid  gives  with  platinum 
chloride  a  crystalline  double  combination  which  is  easily  soluble  in 
water,  insoluble  in  alcohol  and  ether,  and  which  crystallizes  in  six- 
sided  orange-colored  plates.  This  combination  is  used  in  detecting 
this  base. 

Lecithin  occurs,  as  Hoppe-Seyler  has  especially  shown,  widely 
•diffused  in  the  vegetable  and  animal  kingdoms.  According  to  this 
investigator,  it  occurs  also  in  many  cases  in  combination  with 
•other  bodies,  such  as  albuminous  bodies,  hsemoglobin,  and  others. 
Lecithin,  according  to  Hoppe-Setler,  is  found  in  nearly  all  animal 
and  vegetable  cells  thus  far  studied,  and  also  in  nearly  all  fluids. 
It  is  specially  abundant  in  the  brain,  nerves,  fish-eggs,  yolk  of  the 
egg,  electrical  organs  of  the  gymnotus  electricus,  semen  and  pus, 
and  also  in  the  muscles  and  blood-corpuscles,  blood-plasma,  lymph, 
milk,  and  bile,  as  well  as  in  other  animal  juices  and  liquids. 
Lecithin  is  also  found  in  pathological  tissues  or  liquids. 

Lecithin  may  be  obtained  in  grains  or  warty  masses  composed 
of  small  crystalline  plates  by  strongly  cooling  its  solution  in 
strong  alcohol.  In  the  dry  state  it  has  a  waxy  appearance,  is 
mouldable  and  soluble  in  alcohol,  especially  on  heating  (to  40°-50° 
C);  it  is  less  soluble  in  ether.  It  is  dissolved  also  by  chloroform, 
carbon  disulphide,  benzol,  and  fatty  oils.  It  swells  in  water  to  a 
pasty  mass  which  shows  under  the  microscope  slimy,  oily  drops 
and  threads,  so-called  myelin  forms  (see  Chap.  X).  On  warming 
this  swollen  mass  or  the  concentrated  alcoholic  solution,  decom- 
position takes  place  with  the  production  of  a  brown  color.  On 
allowing  the  solution  or  the  swollen  mass  to  stand,  decomposition 


THE  ANIMAL   CELL.  46 

takes  place  and  the  reaction  becomes  acid.  In  putrefying  lecithin 
yields  glyeerophosphoric  acid  and  cholin;  the  latter  further  decom- 
poses with  the  formation  of  methylamin,  ammonia,  carbon  dioxide, 
and  marsh-gas  (Hasebroek).  If  dry  lecithin  be  heated  it  decom- 
poses, takes  fire  and  burns,  leaving  a  phosphorized  coke.  On 
fusing  with  caustic  alkali  and  saltpetre  it  yields  alkali  phosphates. 
Lecithin  is  easily  carried  down  during  the  precipitation  of  other 
compounds  such  as  the  albuminous  bodies,  and  may  therefore  very 
greatly  change  the  solubilities  of  the  latter. 

Lecithin  combines  with  acids  and  bases.  The  combination 
with  hydrochloric  acid  gives  with  platinum  chloride  a  double  salt 
which  is  insoluble  in  alcohol,  soluble  in  ether,  and  which  contains 
10.2^  platinum. 

It  may  be  prepared  tolerably  pure  from  the  yolk  of  the  hen's 
egg  by  the  following  methods,  as  suggested  by  Hoppe-Seyler  and 
DiACOXOW:  The  yolk,  deprived  of  albumin,  is  extracted  with 
cold  ether  until  all  the  yellow  color  is  removed.  Then  the  residue 
is  extracted  with  water  at  50-60°  C.  After  the  evaporation  of  the 
alcoholic  extract  at  50-60°  C,  the  syrupy  matter  is  treated  with 
ether  and  the  insoluble  residue  dissolved  in  as  little  alcohol  as  pos- 
sible. On  cooling  this  filtered  alcoholic  solution  to  —  5"  to— 20° 
C.  the  lecithin  gi-adually  separates  in  small  grains.  According  to 
GiLSOX,  a  new  portion  of  lecithin  may  be  obtained  from  the  ether 
nsed  in  extracting  the  yolk  by  dissolving  the  residue  after  the 
evaporation  of  the  ether  in  petroleum  ether  and  then  shaking  this 
solution  with  alcohol.  The  petroleum  ether  takes  the  fat,  while 
the  lecithin  remains  dissolved  in  the  alcohol  and  may  be  obtained 
therefrom  rather  easily  by  using  the  proper  precautions. 

The  detection  and  the  quantitative  estimation  of  lecithin  in 
animal  fluids  or  tissues  is  based  on  the  solubility  of  the  lecithin  (at 
50-60°  C.)  in  alcohol-ether,  by  which  the  phosphoric  acid  or  glyeero- 
phosphoric acid  salts  which  may  be  present  at  the  same  time  are 
not  dissolved.  The  alcohol-ether  extract  is  evaporated,  the  residue 
dried  and  burnt  with  soda  and  saltpetre.  Phosphoric  acid  is  formed 
from  the  lecithin,  and  it  can  be  detected  and  quantitatively  esti- 
mated. The  distearyllecithin  yields  8.798^  P^Oj-  This  method  is, 
however,  not  exactly  correct,  for  it  is  possible  that  other  phosphor- 
ized organic  combinations,  such  as  jecorin  (see  Chapter  VI),  may 
have  passed  into  the  alcohol-ether  extract.  For  the  detection  of 
lecithin,  boiling  with  baryta-water  and  the  preparation  of  the 
double  platinum  salt  of  cholin  is  sufficient. 

The  study  of  the  second  phosphorized  constituents  of  the  cell, 
the  nuclein,  is  generally  pursued  with  the  study  of  the  cell  nucleus. 


46  PHTSIOLOOIGAL  CHEMISTRY. 

The  Cell  Nucleus,  as  far  as  investigated,  contains  nuclein  as 
chief  constituent. 

Nucleins.  By  this  name  Hoppe-Seyler  and  Miescher  desig- 
nated the  chief  constituent  of  the  nucleus  of  the  pus  cell  first 
isolated  by  them.  Since  that  time,  as  by  continuous  investigations 
the  same  body  is  found  very  widely  diffused  in  the  animal  and 
vegetable  kingdoms,  especially  in  organs  rich  in  cells,  we  now  desig- 
nate as  nuclein  a  number  of  phosphorized  bodies  which  are 
partly  obtained  as  splitting  products  of  the  nucleoalbumins,  and 
partly  the  chief  constituents  of  the  cell  nucleus. 

According  to  Hoppe-Seylee,  these  bodies  may  be  divided  into 
three  groups.  The  first,  to  which  belong  the  nuclein  of  yeast,  pus, 
nucleated  red  blood-corpuscles,  and  probably  the  cell  nucleus  in 
general,  on  boiling  with  acids  yields  as  splitting  products  albumin- 
ous bodies,  xanthin  bodies,  and  phosphoric  acid.  To  the  second 
group,  which  yields  as  splitting  products  albumin  and  phosphoric 
acid,  belong  the  nuclein  of  the  yolk  of  the  egg  and  casein — in  other 
words,  from  the  nucleo-albumins  in  general,  and  to  the  third  group, 
which  gives  as  splitting  products  only  phosj)horic  acid  and  hypoxan- 
thin,  belongs  only  the  nuclein  of  the  sperm  of  the  salmon.  Lieber- 
MANK  has  split  off  metaphosphoric  acid  from  the  nuclein  of  yeast, 
and  he  has  also  found  that  the  metaphosphoric  acid  gives  a  com- 
bination with  albumin  which  acts  like  a  nuclein  of  the  second 
group.  PoHL  has  also  come  to  the  same  result  in  so  far  as  he  has 
been  able  to  prepare  a  combination  of  metaphosphoric  acid  with 
serum  albumin  and  albumose  which  is  similar  to  nuclein.  Lieber- 
MANisr  therefore  considers  nuclein  as  a  combination  between  albumin 
and  metaphosphoric  acid.  The  xanthin  bodies,  which,  according 
to  KossEL,  are  decomposition  products  of  the  nucleins,  according  to 
LiEBERMANN  probably  come  from  admixture. 

That  we  find  different  constitutions  for  nucleins  of  different 
origin  is  not  remarkable.  A  variation  of  3.2-9.6^  in  the  amount 
of  phosphorus  has  been  found  in  different  nucleins.  Under  such 
conditions,  and  as  the  nuclein  question  is  at  present  doubtful,  it 
is  hardly  of  any  use  to  give  the  results  of  the  elementary  analyses 
of  the  different  nucleins. 

The  nucleins  are  colorless,  amorphous,  insoluble,  or  only  slightly 
soluble  in  water.     They  are  insoluble  in  alcohol  and  ether.     Thev 


THE  ANIMAL   CELL.  47 

are  more  or  less  easily  dissolved  by  alkalies  ;  in  dilute  mineral 
acids  'they  are  insoluble  or  dissolve  with  difficulty.  The  nucleins 
are  not  dissolved  by  pepsin-hydrochloric  acid,  or  only  slightly  by  its 
continuous  action.  The  nucleins  containing  albumin  answer  to 
the  biuret  test  and  Millon's  reaction.  With  dilute  mineral  acids 
at  ordinary  temperature  they  give  off  (at  least  for  nuclein  from 
yeast  or  yolk  of  egg)  metaphosphoric  acid.  On  boiling  with 
caustic  alkali  they  decompose  and  alkali  phosphates  are  formed. 
On  burning  they  leave  an  acid-reacting,  difficultly-burnt  coke  which 
contains  metaphosphoric  acid.  On  fusing  with  saltpetre  and  soda 
they  give  alkali  phosphates. 

To  prepare  nucleins  from  nucleoalbumins  casein  is  the  best  ma- 
terial to  employ.  This  is  first  dissolved  in  water  containing  about 
2  p.m  HCl,  the  filtered  solution  treated  with  pepsin  and  digested 
at  the  temperature  of  the  body.  After  a  little  time  a  precipitate  con- 
sisting of  nuclein  ap23ears,  which  is  purified  by  repeated  solution  in 
water  with  tlie  aid  of  the  smallest  quantity  of  alkali,  and  by  repre- 
cipitating  with  acid,  washing  with  water,  and  extracting  with  alcohol 
and  ether.  From  cells  or  tissues  first  remove  the  chief  mass  of  the 
albumins  by  the  artificial  digestion  with  pepsin-hydrochloric  acid, 
digest  the  residue  with  very  dilute  ammonia,  filter,  and  precipitate 
with  hydrochloric  acid.  This  precipitate  is  now  digested  with 
artificial  gastric  juice  and  treated  as  above  described.  In  detecting 
nuclein  the  same  method  is  used,  and  the  last  product  is  fused 
with  soda  and  saltpetre,  and  phosphoric  acid  tested  for  in  the 
melted  mass.  Naturally  the  phosphate  lecithin  (and  jecorin)  must 
first  be  removed  by  acid,  alcohol,  and  ether  respectively.  No  exact 
methods  are  known  for  the  quantitative  estimation  of  the  nucleins 
in^  organs  and  tissues. 

Among  the  decomposition  products  of  the  nucleins  the  so- 
called  xantJiin  bodies  are  especially  of  great  interest.  Although 
LiEBERMANN,  in  Opposition  to  the  views  of  Kossel,  considers 
these  bodies  not  as  real  decomposition  products  of  nuclein,  but 
only  as  admixtures,  yet  until  this  question  is  settled  more  defi- 
nitely, and  since  the  xanthin  bodies  stand  in  close  relationship  to 
the  cell  nucleus,  it  is  perhaps  most  proper  to  speak  of  these  bodies 
in  connection  with  the  cell  nucleus  and  the  nucleins. 

Xanthin  Bodies.  With  this  name  we  designate  a  group  of 
bodies  consisting  of  carbon,  hydrogen,  nitrogen,  and  in  most  cases 


48  PHT8I0L0QICAL  CHEMISTRY. 

also  of  oxygen,  which,  by  their  constitution,  show  a  relationship 
not  only  among  themselves,  but  also  with  uric  acid.  These  bodies 
are  xanthin,  liyijoxanthiii,  guanin,  adenin,  heteroxantMn,  para- 
xanthin,  and  carnin.  The  bodies  theobeomin  and  theophyllin" 
(both  dimethyl  xanthin)  and  caffein  (trimethyl  xanthin)  occur- 
ring in  the  vegetable  kingdom  also  belong  to  this  group.  The 
relation  of  these  bodies  to  one  another  is  shown  in  the  following 
list: 

Uric  acid C6H4N403 

Xanthin €5114X402 

Hypozanthin CsHjIM  4O 

Guanin 05115X50 

Adenin C.EJi, 

Heteroxanthin C6H6N4O3 

Paraxanthin C7  H  eN402 

Carnin C7HeN403 

Guanin  may  be  converted  into  xanthin,  and  adenin  into  hypo- 
xanthin,  by  nitrous  acid,  also  by  putrefaction.  Carnin  is  converted 
,into  hydrobromic-acid  hypoxanthin  by  bromine- water.  Adenin,  as 
is  shown  by.  its  formula,  is  a  polymeric  substance  of  hydrocyanic 
acid,  and  on  its  decomposition  with  alkali  yields  alkali  cyanides. 
The  relationship  of  these  bodies  to  cyanogen  is  also  shown  by 
Gautier,  who  prepared  xanthin  synthetically  from  hydrocyanic 
acid. 

The  significance  of  the  xanthin  bodies  as  decomposition  prod- 
ucts of  the  cell  nucleus  and  of  nuclein  was  first  pointed  out  by 
Kossel,  who  discovered  the  two  bodies  adenin  and  theophyllin, 
and  his  researches  have  greatly  contributed  towards  the  knowledge 
of  xanthin  products.  In  those  tissues  in  which,  as  in  the  glands, 
the  cells  have  kept  their  original  state,  the  xanthin  bodies  are  not 
found  free,  but  in  combination  with  other  atomic  gi'oups  (nu- 
cleins).  In  such  tissue,  on  the  contrary,  as  in  muscles,  which  are 
poor  in  ceil  nuclei,  the  xanthin  bodies  are  found  in  the  free  state. 
If  the  xanthin  bodies,  as  suggested  by  Kossel,  stand  in  close  rela- 
tionship to  the  cell  nucleus,  it  is  easy  to  understand  why  the  mass 
of  these  bodies  is  so  greatly  increased  when  large  quantities  of  nu- 
cleated cells  appear  in  such  places  as  were  before  relatively  poorly 
endowed.  As  an  example  of  this  we  have  in  leucaemia  blood 
extremely  rich  in  leucocytes.     In  such  blood  Kossel  found  1.04 


THE  ANIMAL   CELL.  49 

p.  m.  xanthin  bodies,  against  only  traces  in  the  normal  blood. 
That  the  xanthin  bodies  are  also  intermediate  steps  in  the  forma- 
tion of  urea  or  uric  acid  in  the  animal  organism,  as  will  be  shown 
later  (see  Chapter  XIV),  is  probable. 

Those  xanthin  bodies  which  have  thus  far  been  obtained  in  the 
decomposition  of  the  nucleins,  or  generally  from  cells,  or  from 
tissue  rich  in  cell  nuclei,  and  on  this  account  will  be  described 
here,  are  xanthin,  hypoxanthin,  guanin,  and  adenin,  all  of  which 
are  found  in  the  vegetable  kingdom  (Schulze  and  Bosshard, 
KossEL,  Bagixsky).  The  carnin,  which  has  only  been  found  in 
meat  extracts  (Weidel)  and  in  the  flesh  of  certain  fishes,  as  also 
in  the  bodies  paraxanthin  and  heteroxanthin  (Salomon),  which 
are  only  found  in  urine,  will  be  described  in  their  proper  chapters, 
namely,  IX  and  XIV. 

«.     ,,  .     /-.  T-r  -»-r  /-v        NH.CH  :  C.NH^  ^ „    ,_,    ^  ^     . 

Xanthin,  C.H.N.O,  =  ^^  ,^„     ^^         >  CO   (E.  Fischer),  is 

found  in  the  muscles,  liver,  spleen,  pancreas,  kidneys,  testicles, 
carp-sperm,  thymus,  and  brain.  It  occurs  in  the  smallest  amounts 
as  a  physiological  constituent  of  urine,  and  it  has  been  found  rarely 
as  a  urinary  sediment  or  calculus.  It  was  first  observed  in  such  a 
stone  by  Marcet.  Xanthin  is  found  in  larger  amounts  in  a  few 
varieties  of  guano  (Jarvis  guano). 

Xanthin  is  amorphous,  or  forms  granular  masses  of  crystals. 
It  is  very  slightly  soluble  in  water,  in  14,151-14,600  parts  at 
+  16°  C,  and  in  1300-1500  parts  at  100°  C.  (Almen).  It  is 
insoluble  in  alcohol  or  ether,  but  is  dissolved  by  alkalies  or  acids. 
With  hydrochloric  acid  it  gives  a  crystalline,  difficultly-soluble 
combination.  Xanthin  dissolved  in  ammonia  gives  with  silver 
nitrate  an  insoluble,  gelatinous  precipitate  of  xanthin  silver.  This 
precipitate  is  dissolved  by  nitric  acid,  and  by  this  method  an  easily- 
soluble  double  combination  is  formed.  A  watery  xanthin  solution 
is  precipitated  on  boiling  with  copper  acetate.  At  ordinary  tem- 
peratures xanthin  is  precipitated  by  mercuric  chloride  and  by  am- 
moniacal  lead  acetate. 

When  evaporated  to  dryness  in  a  porcelain  dish  with  nitric  acid 
xanthin  gives  a  yellow  residue,  which  turns,  on  the  addition  of 
caustic  soda,  first  red,  and,  after  heating,  purple  red.  If  we  add 
some  chloride  of  lime  to  some  caustic  soda  in  a  porcelain  dish 


60  PHYSIOLOGICAL   CHEMI8TET. 

and  add  the  xantliin  to  this  mixture,  at  first  a  dark  green  and  then 
quickly  a  brownish  halo  forms  around  the  xanthin  grains  and  then 
disappears  (Hoppe-Setlee).  If  xanthin  be  warmed  in  a  small 
vessel  on  the  water-bath  with  chlorine-water  and  a  trace  of  nitric 
acid  and  evaporated  to  dryness,  when  the  residue  is  exposed  under 
a  bell-jar  to  the  vapors  of  ammonia  a  red  or  purple-violet  color  is 
produced  (Weidel^s  reaction).  It  is  still  a  question  whether  en- 
tirely pure  xanthin  will  give  this  reaction. 

Hypoxanthin  or  Sarkin,  C.H^JST.O.  This  body  is  found  in  the 
tissues  containing  xanthin.  It  is  especially  abundant  in  the  sperm 
of  salmon  and  carp.  It  occurs  also  in  the  marrow.  In  normal 
urine  it  appears  in  very  small  quantities,  and  it  seems  also  to  be 
found  in  milk.  It  is  found  in  rather  significant  quantities  in  the 
blood  and  urine  in  leucocyth^mia. 

Hypoxanthin  forms  very  small  colorless  crystalline  needles.  It 
is  more  soluble  than  xanthin.  It  dissolves  in  300  parts  cold  and 
78  parts  boiling  water.  It  is  nearly  insoluble  in  alcohol,  but  it  is 
dissolved  by  alkalies  and  acids.  The  combination  with  hydrochloric 
acid  crystallizes  and  is  more  soluble  than  the  corresponding  xanthin 
combination.  It  acts  in  ammoniacal  solution  like  xanthin  with 
silver  nitrate.  The  silver  combination  of  hypoxanthin  dissolves 
with  difl&culty  in  boiling  nitric  acid  of  1.1  sp.  gr.,  and  on  cooling 
the  double  combination  separates  as  crystalline  needles.  Treated 
like  xanthin  with  nitric  acid,  hypoxanthin  gives  a  nearly  colorless 
residuum  which  does  not  become  red  by  heating  with  alkali.  Hypo- 
xanthin does  not  give  Weidel's  reaction.  After  the  action  of 
hydrochloric  acid  and  zinc  a  hypoxanthin  solution  becomes  first 
ruby-red  and  then  brownish  red  in  color  on  the  addition  of  an  excess 
of  alkali  (Kossel). 

:N^H.CH:C.NH     ^^        ^       .       . 
Guanin,    C!,H,N,0  =  ^j^ .  ^5  j^jj      ^,^^  >C0.      Guanm    is 

found  in  organs  rich  in  cells,  such  as  the  liver,  spleen,  pancreas,  testi- 
cles, and  in  salmon-sperm.  It  is  further  found  in  the  muscles  (in  very 
small  amounts),  in  the  scales  and  in  the  air-bladder  of  certain  fishes 
as  iridescent  crystals  of  guanin  lime;  in  the  retina  epithelium  of 
fishes,  in  guano,  and  in  the  excrement  of  spiders  it  is  found  as  chief 
constituent.     Under  pathological  conditions  it  has  been  found  in 


THE  ANIMAL  CELL.  61 

leucocythfemic  blood,  and  in  the  muscles,  ligaments,  and  articula- 
tions of  pigs  with  guanin  gout. 

Guanin  is  a  colorless,  ordinarily  amorphous  powder  which  may 
be  obtained  as  small  crystals  by  allowing  its  solution  in  concentrated 
ammonia  to  spontaneously  evaporate.  It  is  nearly  insoluble  in 
water,  alcohol,  and  ether.  It  is  easily  dissolved  by  mineral  acids 
and  alkalies,  but  it  dissolves  with  great  difficulty  in  ammonia. 
The  silver  combination  dissolves  with  difficulty  in  boiling  nitric 
acid,  and  on  cooling  the  double  combination  crystallizes.  Guanin 
acts  like  xanthin  in  the  nitric-acid  test,  but  gives  with  alkalies  on 
heating  a  stronger  bluish-violet  color.  A  warm  solution  of  guanin 
hydrochloride  gives  with  a  cold  saturated  solution  of  picric  acid 
a  yellow  precipitate  consisting  of  silky  needles  (Capeanica).  "With 
a  concentrated  solution  of  potassium  chromate  a  guanin  solution 
^ves  a  crystalline,  orange-red  precipitate,  and  with  a  concentrated 
solution  of  potassium  ferricyanide  a  yellowish  brown,  crystalline 
precipitate  (Capeanica). 

Adenin,  C-H^N^,  was  first  found  by  Kossel  in  the  pancreas 
gland.  It  occurs  in  greatest  quantities  in  the  sperm  of  the  carp 
and  in  the  thymus  (Kossel  and  Schmidlee).  It  also  occurs  in 
the  liver,  spleen,  lymphatic  glands,  and  kidneys  (not  in  muscles). 
It  has  been  observed  in  leucocythsemic  urine. 

Adenin  crystallizes  in  long  needles.  It  dissolves  in  cold  water 
with  difficulty  (1086  parts),  but  easily  in  warm.  Pure  adenin  dis- 
solves slightly  in  boiling  alcohol,  in  cold  not  at  all ;  impure  adenin 
is,  however,  dissolved  by  cold  alcohol.  It  is  insoluble  in  ether. 
Adenin  is  easily  dissolved  by  acids  and  alkalies.  In  dilute  ammo- 
nia it  dissolves  with  more  difficulty  than  hypoxanthin,  but  more 
easily  than  guanin.  The  silver  combination  dissolves  with  difficulty 
in  boiling  nitric  acid  and  crystallizes  on  cooling.  The  nitric-acid 
test  and  Weidel's  reaction  act  the  same  as  with  bypoxanthin. 
The  same  is  true  for  its  behavior  with  hydrochloric  acid  and  zinc 
with  addition  of  alkali. 

The  principle  for  the  preparation,  detection,  and  the  quantitative 
estimation  of  the  four  above-described  xanthin  bodies  is,  according  to 
Kossel  and  Kossel  and  Schindlee,  as  follows :  The  finely-divided 
organ  or  tissue  is  boiled  for  three  or  four  hours  with  sulphuric  acid 
of  about  5  p.  m.     The  filtered  liquid  is  freed  from  albumin  by  lead 


52  PHYSIOLOGICAL   CHEMISTRY. 

acetate,  and  the  new  filtrate  is  treated  with,  sulphuretted  hydrogenr 
to  remove  the  lead,  again  filtered,  concentrated,  and,  after  adding 
an  excess  of  ammonia,  precipitated  with  silver  nitrate.  The  silver 
combination  (with  the  addition  of  some  urea  to  prevent  nitrification) 
is  dissolved  in  not  too  large  a  quantity  of  boiling  nitric  acid  of  sp. 
gr.  1.1,  and  this  solution  filtered  boiling  hot.  On  cooling  the  silver 
xanthin  remains  in  the  solution,  while  the  double  combination  of 
guanin,  hypoxanthin,  and  adenin  crystallizes.  The  xanthin  silver 
may  be  removed  from  the  filtrate  by  the  addition  of  ammonia,  and 
the  xanthin  set  free  by  means  of  sulphuretted  hydrogen.  The 
three  above-mentioned  silver  nitrate  combinations  are  decomposed 
in  water  with  ammonium  sulphide  and  heat;  the  silver  sulphide  is 
filtered,  the  filtrate  concentrated,  saturated  with  ammonia,  and 
digested  on  the  water-bath.  The  guanin  remains  undissolved, 
while  the  other  two  bases  pass  into  solution.  A  part  of  the  guanin 
is  still  retained  by  the  silver  sulphide,  and  may  be  liberated  by 
boiling  it  with  dilute  hydrochloric  acid  and  then  saturating  the 
filtrate  with  ammonia.  When  the  above  filtrate,  containing  the 
adenin  and  hypoxanthin,  which  has  been,  if  necessary,  freed 
from  ammonia  by  evaporation,  is  allowed  to  cool,  the  adenin 
separates,  while  the  hypoxanthin  remains  in  solution.  The  chief 
points  in  the  above  'method  are  used  for  the  quantitative  esti- 
mation of  the  xanthin  bodies.  If  the  solution  of  adenin  and 
hypoxanthin  is  evaporated  to  dryness,  the  residue  weighed,  and  the 
amount  of  nitrogen  determined,  from  this  determination  and  from 
the  amount  of  nitrogen  in  hypoxanthin  (41.1*7^)  and  in  adenin 
(51.87^)  the  quantity  of  each  of  these  bodies  may  be  calculated. 

In  the  generative  animal  cells,  and  especially  in  those  which 
develop  embryonic  tissue,  Cl.  Bernard  and  Hensen  have  dis- 
covered a  carbohydrate,  the  glycogen.  According  to  Hoppe- 
Seyler  it  seems  to  be  a  never-failing  constituent  of  the  cells  as 
soon  as  they  show  embryonic  movements,  and  he  found  this  carbo- 
hydrate in  the  white  blood-corpuscles  but  not  in  the  developed 
motionless  pus-corpuscles.  The  relationship  which  exists  between 
the  consumption  of  glycogen  and  muscular  work  (see  Chapter  IX) 
leads  us  to  suppose  that  such  a  consumption  takes  place  in  the 
movements  of  the  animal  protoplasm.  On  the  other  side  the 
widely-diffused  occurrence  of  glycogen  in  embryonic  tissues,  as 
also  its  occurrence  in  pathological  swellings  and  in  abundant  cell- 
formations,  seems  of  the  greatest  importance  in  the  formation  and 
development  of  the  cell. 

In  grown  animals  the  glycogen  is  found  in  the  muscles  and 


THE  ANIMAL   CELL.  53 

certain  other  organs,  foremost  of  these  being  the  liver;  it  will 
therefore  be  more  thoroughly  described  in  connection  with  this 
organ  (Chapter  VI). 

Another  body  or  more  correctly  a  group  of  bodies  which  occur 
very  widely  diffused  in  the  animal  and  vegetable  kingdoms  and 
habitually  in  the  cells  are  the  cholesterines,  whose  best-known 
tepresentative  is  the  ordinary  cholestefm,  specially  known  as  the 
chief  constituent  of  certain  biliary  calculi  and  occurring  in  large 
quantities  in  the  brain  and  nerves.  It  is  hardly  to  be  admitted  that 
this  body  has  any  direct  importance  in  the  life  and  the  develop- 
ment of  the  cell.  It  is  more  probable,  as  Hoppe-Seyler  suggests, 
that  cholesterin  is  a  splitting  product  appearing  in  the  general  life- 
processes  of  the  cells.  Also  according  to  Hoppe-Seyler  the  fat, 
which  does  not  constantly  appear  in  the  cell,  has  nothing  to  do 
with  the  general  process  of  life. 

Mineral  bodies  are  also  never-failing  constituents  of  the  cell. 
These  minerals  are  potassium,  sodium,  calcium,  magnesium,  iron, 
phosphoric  acid,  and  chlorine.  In  regard  to  the  alkalies  we  find  in 
general  in  the  animal  organism  that  the  sodium  combinations  are 
more  abundant  in  the  fluids,  the  potassium  combinations  occur 
chiefly  in  the  form-constituents  and  in  the  protoplasm.  Corre- 
sponding to  this  the  cell  contains  potassium,  chiefly  as  phosphate, 
while  the  sodium  and  chlorine  combinations  occur  less  abundantly. 
According  to  the  ordinary  views  the  potassium  combinations,  espe- 
cially the  potassium  phosphate,  are  of  the  greatest  importance  for 
the  life  and  development  of  the  cell,  even  though  we  do  not  know 
the  nature  of  the  importance.  At  least  we  must  not  overlook  the 
fact  that  a  part  of  the  phosphoric  acid  which  is  obtained  from  the 
cell  or  tissue  rich  in  cells  may  originate  from  the  nuclein  and  leci- 
thin in  the  process  of  ashing.  Also  the  iron,  which  often  occurs  in 
the  ash  as  ferric  phosphate,  seems,  at  least  in  part,  to  be  formed 
from  the  nucleo-albumin.  The  habitual  occurrence  of  earthy 
phosphates  in  all  cells  and  tissues,  together  with  the  difficulty  or 
almost  impossibility  of  separating  these  bodies  from  the  protein 
substances  without  decomposition,  leads  us  to  suppose  that  these 
mineral  bodies  are  indeed,  though  their  role  is  still  unknown,  of 
the  greatest  importance  for  the  life  of  the  cells  and  the  chemical 
processes  which  accompany  their  evolution. 


CHAPTER  IV. 


THE  BLOOD. 


The  blood  is  to  be  considered  from  a  certain  standpoint  as  a 
fluid  tissue,  and  it  consists  of  a  transparent  liquid,  the  Mood- 
plasma,  in  which  an  immense  number  of  solid  particles,  the  red 
and  colorless  Mood-corpuscles  (and  the  Mood-taMets)  are  suspended. 

Outside  of  the  organism  the  blood,  as  is  well  known,  coagulates 
more  or  less  quickly;  but  this  coagulation  is  accomplished  gener- 
ally in  a  few  minutes  after  leaving  the  body.  All  varieties  of  blood 
do  not  coagulate  with  the  same  degree  of  rapidity.  Some  coagulate 
more  quickly,  others  more  slowly.  Among  the  varieties  of  blood 
thus  far  investigated  the  blood  of  the  horse  coagulates  most  slowly. 
The  coagulation  may  be  more  or  less  retarded  by  quickly  cooling; 
and  if  we  allow  equine  blood  to  flow  directly  from  the  vein  into  a 
glass  cylinder  which  is  not  too  wide  and  which  has  been  cooled, 
and  let  it  stand  at  0°  C,  the  blood  may  be  kept  fluid  for  several 
days.  An  upper,  amber-yellow  layer  of  plasma  gradually  separates 
from  a  lower,  red  layer  composed  of  blood-corpuscles  with  only  a 
little  plasma.  Between  these  we  observe  a  whitish-gray  layer, 
which  consists  of  white  blood-corpuscles. 

The  plasma  thus  obtained  and  filtered  is  a  clear  amber-yellow 
alkaline  liquid  which  remains  fluid  for  some  time  when  kept  at  0° 
C,  but  soon  coagulates  at  the  ordinary  temperature. 

The  coagulation  of  the  blood  may  be  prevented  in  other  ways. 
After  the  injection  of  peptone  or,  more  correctly,  albumose  solu- 
tions into  the  blood  (in  the  living  dog),  the  blood  does  not 
coagulate  on  leaving  the  veins  (Fako,  Schmidt-Miilheim).  The 
plasma  obtained  from  such  blood  by  means  of  centrifugal  force  is 
called  "peptone-plasma"     The  coagulation  of  the  blood  of  warm- 

54 


THE  BLOOD.  55 

blooded  animals  is  prevented  by  the  injection  of  an  effusion  of  the 
mouth  of  the  oflScinal  leech  into  the  blood-current  (Haycraft). 
If  the  blood-circulation  of  a  dog  is  cut  off  between  the  liver  and 
intestines  and  the  blood  allowed  to  flow  only  through  the  head  and 
the  viscera  of  the  thoracic  cavity,  the  coagulation  of  the  blood  is 
destroyed  (Pawlow,  Bohr).  If  we  alloM  the  blood  to  flow 
directly,  while  we  stir  it,  into  a  neutral  salt  solution — best  a  satu- 
rated magnesium  sulphate  solution  (1  vol.  salt  solution  and  3 
vols,  blood) — we  obtain  a  mixture  of  blood  and  salt  which  re- 
mains uncoagulated  for  several  days.  The  blood-corpuscles  which, 
because  of  their  adhesiveness  and  elasticity,  would  otherwise  pass 
easily  through  the  pores  of  the  filter-paper  are  made  solid  and  stiff 
by  the  salt,  so  that  they  may  be  easily  filtered.  The  plasma  thus 
obtained,  which  does  not  coagulate  spontaneously,  is  called  "  salt- 
plasma" 

On  coagulation  there  separates  in  the  previously  fluid  blood  an 
insoluble  or  a  very  difficultly-soluble  albuminous  substance, ^Jmi. 
When  this  separation  takes  place  without  stirring  the  blood  coagu- 
lates to  a  solid  mass  which,  when  carefully  severed  from  the  sides 
of  the  vessel,  contracts,  and  a  clear,  generally  yellow-colored  liquid, 
the  Mood-serum,  exudes.  The  solid  coagulum  wjiicli  incloses  the 
blood-corpuscles  is  called  the  hlood-clot  (placenta  sanguinis).  If 
the  blood  is  beaten  during  coagulation,  the  fibrin  separates  in 
elastic  threads  or  fibrous  masses,  and  the  defihrinated  blood  which 
separates  is  sometimes  called  cruor,^  and  consists  of  blood-cor- 
puscles and  blood-serum. 

The  defihrinated  blood  consists  of  blood-corpuscles  and  serum, 
while  the  uncoagulated  blood  consists  of  blood-corpuscles  and 
blood -plasma.  The  essential  chemical  difference  between  blood- 
serum  and  blood-plasma  is  that  the  blood-serum  does  not  contain 
the  mother-substance  of  fibrin,  the  fibrinogen,  which  exists  in  the 
blood-plasma,  and  the  serum  is  proportionally  richer  in  another 
body,  the  fibrin  ferment  (see  page  58), 

'  The  name  cruor  is  used  in  different  senses.  We  sometimes  understand 
thereby  only  the  blood  when  coagulated  to  a  red  solid  mass,  in  other  cases 
the  blood-clot  after  the  separation  of  the  serum,  and  lastly  the  sediment  con-^ 
sisting  of  red  blood-corpuscles  which  is  obtained  from  defibrinated  blood  by 
means  of  centrifugal  force  or  by  letting  it  stand. 


66  PHYSIOLOGICAL  CHEMISTBT. 

I.  Blood-plasma  and  Blood-serum. 
The   Blood-plasma. 

In  tlie  coagulation  of  the  blood  a  chemical  transformation  takes 
place  in  the  plasma.  A  part  of  the  albumins  separates  as  insoluble 
fibrin.  The  albuminous  bodies  of  the  plasma  must  therefore  be 
first  described.  They  are  fibrinogen,  serum  glohulhi,  and  serum 
albumin. 

Fibrinogen  occurs  in  blood-plasma,  chyle,  lymph,  and  in  certain 
transudations  and  exudations.' 

It  has  the  general  properties  of  the  globulins,  but  differs  from 
other  globulins  as  follows:  In  a  moist  condition  it  forms  white 
flakes  which  are  soluble  in  dilute  common  salt  solutions,  and 
which  easily  conglomerate  into  tough,  elastic  masses  or  lumps. 
The  solution  in  NaCl  of  5-10 fo  coagulates  on  heating  to  -}-  52° 
to  55°  C,  and  the  faintly  alkaline  or  nearly  neutral  weak  salt 
solution  coagulates  at  +  56°  C,  or  at  exactly  the  same  tem- 
perature at  which  the  blood-plasma  coagulates.  Fibrinogen  solu- 
tions are  precipitated  by  an  equal  volume  of  a  saturated  common 
salt  solution,  and  are  completely  precipitated  by  adding  an  excess 
of  NaCl  in  substance  (thus  differing  from  serum  globulin).  It 
differs  from  myosin  of  the  muscles,  which  coagulates  at  about  the 
same  temperature,  and  from  other  albuminous  bodies,  in  the  prop- 
erty of  being  converted  into  fibrin  under  certain  conditions.  Fi- 
brinogen has  a  strong  decomposing  action  on  hydrogen  peroxide. 

The  fibrinogen  may  be  easily  separated  from  the  salt-plasma  by 
precipitation  with  an  equal  volume  of  a  saturated  JSTaCl  solution. 
For  further  purification  the  precipitate  is  pressed,  redissolved  in 
an  8fo  salt  solution,  the  filtrate  precipitated  by  a  saturated  salt 
solution  as  above,  and  after  precipitating  in  this  way  three  times, 
the  precipitate  at  last  obtained  is  pressed  between  filter-paper  and 
finely  divided  in  water.  The  fibrinogen  dissolves  with  the  aid  of 
the  small  amount  of  NaCl  contained  in  itself,  and  the  solution  may 
be  made  salt-free  by  dialysis  with  very  faintly  alkaline  water.  From 
transudations  we  ordinarily  obtain  a  fibrinogen  which  is  strongly 


1  The  question  as  to  the  occurrence  of  other  fibrinogens  (Wooldridge) 
will  be  spoken  of  in  connection  with  the  complete  discussion  of  the  coagula- 
tion of  the  blood.    (See  further  on.) 


THE  BLOOD.  57 

contfiminated  with  lecithin  and  which  can  hardly  be  purified  with- 
out decomposing.  The  method  for  the  detection  and  quantitative 
estimation  of  fibrinogen  in  a  liquid  is  based  on  its  property  of 
yielding  fibrin  on  the  addition  of  a  little  blood,  of  serum,  or  of 
fibrin  ferment. 

The  fibrinogen  stands  in  close  relation  to  its  transformation- 
product,  the  fibrin. 

Fibrin  is  the  name  of  that  albuminous  body  which  separates  on 
the  so-called  spontaneous  coagulation  of  blood,  lymph,  and  trans- 
udations, as  also  in  the  coagulation  of  a  fibrinogen  solution  after  the 
addition  of  serum  or  fibrin  ferment  (see  below). 

If  the  blood  is  beaten  during  coagulation,  the  fibrin  separates  in 
elastic  fibrous  masses.  The  fibrin  of  the  blood-clot  may  be  beaten 
to  small,  less  elastic,  and  not  particularly  fibrous  lumps.  The 
typical,  fibrous,  and  elastic  white  fibrin,  after  washing,  stands  in 
regard  to  its  solubility  close  to  the  coagulable  albuminous  bodies. 
It  is  insoluble  in  water,  alcohol,  or  ether.  It  expands  in  hydro- 
chloric acid  of  1  p.  m.,  as  also  in  caustic  potash  or  soda  of  1  p.  m., 
to  a  gelatinous  mass,  which  dissolves  at  the  ordinary  temperature 
only  after  several  days,  but  at  the  temperature  of  the  body  it  dis- 
solves more  readily  but  still  slowly.  The  fibrin  expands  in  a  5- 
10^  solution  of  common  salt  or  saltpetre,  but  only  dissolves  in 
the  presence  of  contaminating  enzymes  or  by  putrefaction.  Fibrin 
decomposes  hydrogen  peroxide,  but  this  property  is  destroyed  by 
heating  or  by  the  action  of  alcohol. 

What  has  been  said  of  the  solubility  of  fibrin  relates  only  to  the 
typical  fibrin  obtained  from  the  arterial  blood  of  mammalia  or  man 
by  whipping  and  washing  first  with  water  and  with  common-salt 
solution,  and  then  with  water  again.  The  blood  of  various  kinds 
of  animals  yields  fibrin  with  somewhat  different  properties  and 
of  varying  purity,  and  likewise  blood  from  different  parts  of  the 
body  may  yield  fibrim  with  unlike  solubilities  (Denis). 

The  fibrin  obtained  by  beating  the  blood  and  purified  as  above 
described  is  always  contaminated  by  enclosed  blood-corpuscles  or 
remains  thereof,  and  also  by  lymphoid  cells.  It  can  only  be  obtained 
pure  from  filtered  plasma  or  filtered  transudations.  For  the  pure 
preparation,  as  well  as  for  the  quantitative  estimation  of  fibrin,  the 
spontaneously  coagulating  liquid  is  at  once,  or  the  non-spontaneously 
coagulating  liquid  only  after  the  addition  of  blood-serum  or  fibrin 


58  PHYSIOLOGICAL   CHEMISTRY. 

ferment,  thoroughly  beaten  with  a  glass  rod  or  whale-bone,  and  the 
separated  coagulum  is  washed  first  in  water,  and  then  with  a  h% 
common-salt  solution,  and  again  with  water,  and  lastly  extracted 
with  alcohol  and  ether. 

A  pure  fibrinogen  solution  may  be  kept  at  the  ordinary  tempera- 
ture until  putrefaction  begins  without  showing  a  trace  of  fibrin 
coagulation.  But  if  to  this  solution  we  add  a  water-washed  fibrin 
clot  or  a  little  blood-serum,  it  immediately  coagulates  and  may 
yield  perfectly  typical  fibrin.  The  transformation  of  the  fibro- 
gen  into  fibrin  requires  the  presence  of  another  body  contained 
in  the  blood-clot  and  in  the  serum.  This  body,  whose  importance 
in  the  coagulation  of  fibrin  was  first  observed  by  Buchanan,  was 
later  rediscovered  by  Alexander  Schmidt,  and  designated  "fibrin 
ferment."  The  nature  of  this  enzymotic  body  has  not  been  ascer- 
tained. According  to  the  investigations  of  Gam  gee.  Lea,  and 
Green  and  Halliburton,  the  "  fibrin  ferment "  seems  to  be  a 
substance  of  the  nature  of  the  globulins.  According  to  Halli- 
burton, it  is  a  body  derived  from  the  lymphoid  cells,  a  special 
globulin, "  cell-globulin,"  which  differs  from  serum  globulin  partly  by 
fibrino-plastic  properties  and  partly  by  having  another  temperature 
of  coagulation  (-(-  60°  C,  or  somewhat  higher  in  a  solution  contain- 
ing 10^  JSTaCl).  The  so-called  fibrin  ferment  corresponds  to  the 
enzymes  in  that  only  the  very  smallest  amounts  of  it  are  required 
for  action,  and  further  that  on  heating  the  solution  it  becomes  in- 
active. 

The  isolation  of  the  fibrin  ferment  has  been  tried  in  several 
ways.  Ordinarily  it  may  be  prepared  by  the  following  method 
proposed  by  Alex.  Schmidt  :  Precipitate  the  serum  or  defibrinated 
blood  with  15-20  vols,  of  alcohol  and  allow  it  to  stand  a  few  months. 
The  precipitate  is  then  filtered  and  dried  over  sulphuric  acid.  The 
ferment  may  be  extracted  from  the  dried  powder  by  means  of 
water. 

If  a  fibrinogen  solution  containing  salt,  as  above  described,  is 
treated  with  a  solution  of  "  fibrin  ferment,"  it  coagulates  at  the 
ordinary  temperature  more  or  less  quickly  and  yields  a  typical 
fibrin.  Besides  the  fibrin  ferment  the  presence  of  neutral  salts  is 
necessary,  for  without  them  Alex.  Schmidt  has  shown  the  coagu- 
lation of  fibrin  does  not  take  place.    The  amount  of  fibrin  obtained 


THE  BLOOD.  59 

on  coagulation  is  always  smaller  than  the  amount  of  fibrinogen  from 
which  the  fibrin  is  derived,  and  we  always  find  a  small  amount  of 
globulin  substance  in  the  solution.  It  is  therefore  not  improbable 
that  the  coagulation  of  fibrin,  in  accordance  with  the  views  of  Denis, 
is  a  splitting  process  in  which  the  soluble  fibrinogen  is  split  into  an 
insoluble  albuminous  body,  the  fibrin,  which  forms  the  chief  mass, 
and  a  soluble  globulin  substance,  which  is  only  formed  in  small 
amounts.  The  globulin  substance,  which  is  called  "fibrin  globulin  " 
by  the  author,  coagulates  at  +  64°  C.  and  has  the  following  com- 
position :  C  52.70^  ;  H  6.98$^  ;  N  16.06^. 

The  coagulation  of  the  blood  consists  chiefly  in  the  conversion 
of  the  fibrinogen  of  the  plasma  into  fibrin.  The  coagulation  of  the 
blood  is  a  much  more  complicated  process  than  the  coagulation  of 
a  fibrinogen  solution,  inasmuch  as  the  first  involves  other  important 
questions,  as,  for  instance,  the  reason  for  the  blood  remaining  fluid 
in  the  body,  the  origin  of  the  fibrin  ferment,  and  the  importance  of 
the  form-elements  in  the  coagulation.  A  fuller  discussion  of  the 
various  hypotheses  and  theories  concerning  the  coagulation  of  the 
blood  must  therefore  be  given  later. 

Serum  Globulin,  also  called  paraglobulin  (Kuhne),  fibrino- 
plastic  substance  (Alex.  Schmidt),  serum  casein  (Panum),  fibrine 
soluble  (Denis),  occurs  in  the  plasma,  serum,  lymph,  transudations 
and  exudations,  in  the  white  and  red  corpuscles,  and  probably  in 
many  animal  tissues  and  form-elements,  though  in  small  quantities. 
It  is  also  found  in  the  urine  in  many  diseases. 

Serum  globulin  has  the  general  properties  of  the  globulins.  In 
a  moist  condition  it  forms  a  snow-white  flaky  mass  neither  tough 
nor  elastic.  The  essential  differences  between  serum  globulin  and 
fibrinogen  are  the  following:  Serum-globulin  solutions  are  only 
incompletely  precipitated  by  adding  NaCl  to  saturation,  and  not 
precipitated  at  all  by  an  equal  volume  of  a  saturated  common-salt 
solution.  The  coagulation  temperature  is,  with  5-10^  NaCl  in 
solution,  -f  75°  C.  It  is  completely  precipitated  by  MgSO^  in  sub- 
stance added  to  saturation,  as  also  by  an  equal  volume  of  a  sat- 
urated solution  of  ammonium  sulphate.  The  specific  rotary  power, 
according  to  Fredericq,  for  serum  globulin  (from-ox  blood)  solu- 
tions containing  salt  is  «'(D)  =  —  47.8"". 


60  PHYSIOLOGICAL   CHEMISTRY. 

Serum  globulin  may  be  easily  separated  as  a  fine  flocculent  pre- 
cipitate from  blood-serum  by  neutralizing  or  making  faintly  acid 
with  acetic  acid  and  then  diluting  with  10-20  vols,  of  water.  For 
further  purification  this  precipitate  is  dissolved  in  dilute  common- 
salt  solution,  or  in  water  by  the  aid  of  the  smallest  possible  amount 
of  alkali,  and  then  reprecipitated  by  diluting  with  water  or  by  the 
addition  of  a  little  acetic  acid.  The  serum  globulin  may  also  be 
separated  from  the  serum  by  means  of  magnesium  or  ammonium 
sulphate;  in  these  cases  it  is  difficult  to  completely  remove  the  salt 
by  dialysis.  The  serum  globulin  from  blood-serum  is  always  con- 
taminated by  lecithin  and  the  so-called  fibrin  ferment.  A  serum 
globulin  free  from  fibrin  ferment  may  be  prepared  from  ferment- 
free  transudations,  as  sometimes  from  hydrocele  fluids,  and  this 
shows  that  the  serum  globulin  and  the  fibrin  ferment  are  different 
bodies.  For  the  detection  and  the  quantitative  estimation  of  serum 
globulin  we  may  use  the  precipitation  by  magnesium  sulphate  ■ 
added  to  saturation  (authoe),  or  by  an  equal  volume  of  a  saturated 
neutral  ammonium  sulphate  solution  (Hofmeister  and  Kauder 
and  Pohl).  In  the  quantitative  estimation  the  precipitate  is  col- 
lected on  a  weighed  filter,  washed  with  the  salt  solution  employed, 
dried  with  the  filter  at  about  115°  C,  then  washed  with  boiling- 
hot  water,  so  as  to  completely  remove  the  salt,  extracted  with 
alcohol  and  ether,  dried,  weighed  and  burnt  to  determine  the 
ash. 

Serum  Albumin  is  found  in  large  quantities  in  blood-serum, 
blood-plasma,  lymph,  transudations,  and  exudations.  Probably  it 
also  occurs  in  other  animal  liquids  and  tissues.  The  albumin 
which  passes  into  the  urine  under  pathological  conditions  consists 
largely  of  serum  albumin. 

In  the  dry  state  serum  albumin  forms  a  transparent,  gummy, 
brittle,  hygroscopic  mass,  or  a  white  powder  which  may  be  heated 
to  100°  C.  without  decomposing.  Its  solution  in  water  gives  the 
ordinary  reactions  for  albumin;  the  specific  rotary  power  for  serum 
albumin  free  from  paraglobulin,  obtained  from  human  transuda- 
tions, is,  according  to  Stark,  «r(D)  =  —  62.6°  to  —  64.6°.  The 
coagulation  temperature  of  a  serum-albumin  solution  is  +  70°  to 
-}-  75°  C,  according  to  most  authorities,  but  this  varies  to  a  great 
extent  with  a  varying  concentration  and  amount  of  salt.  A  1-2^^ 
albumin  solution  may,  in  the  presence  of  very  little  NaCl,  coagu- 
late at  -|-  50°  C.  or  below;  in  the  presence  of  5^  NaCl  it  coagulates 


THE  BLOOD.  61 

at  +  "^5°  to  +  90°  C.  By  the  careful  addition  of  acid  the  coagula- 
tion temperature  may  be  lowered;  by  the  addition  of  alkali  it  may 
be  raised.  In  blood-serum  from  certain  animals  and  in  human 
transudations  Hallibukton  found  the  coagulation  to  take  place 
on  heating  to  the  following  temperatures:  +  70°  to  73°  C. ;  77°  to 
78°  C;  and  82°  to  85°  C.  He  therefore  considers  the  serum 
albumin  a  mixture  of  three  albumins,  a,  fi,  and  y,  which  coagulate 
at  the  three  points  mentioned.  In  cold-blooded  animals  he  found 
only  the  albumin  a. 

The  serum  albumin  differs  from  the  albumin  of  the  white  of 
the  hen's  ^gg  in  the  following  particulars :  it  is  more  laevogyrate  \ 
the  precipitate  formed  by  hydrochloric  acid  easily  dissolves  in  an 
excess  of  the  acid;  it  is  much  less  insoluble  in  alcohol;  and  lastly 
it  acts  differently  inside  of  the  organism.  If  egg-albumin  is  intro- 
duced into  the  blood  system  it  passes  into  the  urine,  while  the 
serum  albumin  does  not.  A  solution  of  serum  albumin  positively 
free  from  mineral  bodies  has  never  yet  been  prepared.  A  solution 
as  poor  as  possible  in  salts  does  not  coagulate  either  on  boiling 
or  on  the  addition  of  alcohol.  After  the  addition  of  a  little 
common  salt  it  coagulates  in  both  cases. 

In  preparing  serum  albumin,  first  remove  the  globulins  by 
saturating  with  magnesium  sulphate  at  about  -|-  30°  C,  and  filter 
at  the  same  temperature.  The  cooled  filtrate  is  separated  from 
the  crystallized  salt  and  is  treated  with  acetic  acid  of  about  1^. 
The  precipitate  formed  is  filtered,  pressed,  dissolved  in  water 
with  the  addition  of  alkali  to  neutral  reaction,  and  the  solution 
freed  from  salt  by  dialysis.  The  serum  albumin  may  also  be  sepa- 
rated from  the  filtrate  saturated  with  magnesium  sulpliate  bv 
adding  sodium  sulphate  to  saturation  at  about  +  40°  C.  The 
pressed  precipitate  is  also  in  this  case  dissolved  in  water  and  the 
solution  freed  from  salt  by  dialysis.  The  albumin  may  be  obtained 
in  a  solid  form  from  the  dialyzed  solution  either  by  evaporating 
the  solution  to  dryness  at  gentle  heat  or  by  precipitating  with 
alcohol,  which  must  be  removed  quickly.  In  the  detection  and 
quantitative  estimation  of  serum  albumin,  the  filtrate  from  the 
globulins  which  have  been  removed  by  magnesium  sulphate  is 
heated  to  boiling,  after  the  addition  of  a  little  acetic  acid  if  neces- 
sary. The  simplest  way  is  to  consider  the  difference  between  the 
total  albumins  and  the  globulins  as  serum  albumin. 


H 

N 

S 

0 

6  90 

16.66 

1.25 

22.26  (Hammarsten.) 

6.83 

16  91 

1.10 

22.48 

6  98 

16.06 

7.01 

15.85 

I'.ii 

23.24 

6.85 

16.04 

1.80 

22.26 

6.65 

15.88 

2  25 

22.95 

62  PH78I0L0OIGAL   CHEMI8TBT. 

Summary  of  the  elementary  composition  of  the  above  mentioned  and 
described  albuminous  bodies: 
C 

Fibrinogen 52.93 

Fibrin 52.68 

Fibrin  globulin 52.70 

Serum  globulin ....  52.71 
Serum  aibumiu  (1)..  53.06 
Serum  albumin  (2)..  5i.25 

The  serum  albumin  (2)  came  from  a  human  exudation,  and  the  other  bodies 
from  the  blood  of  a  horse.  The  fibrin  was  prepared  from  a  filtered  common- 
salt  plasma. 

The  Blood-serum. 

As  above  stated,  the  blood-serum  is  the  clear  liquid  which  is 
pressed  out  by  the  contraction  of  the  blood-clot.  It  differs  chiefly 
from  the  plasma  in  the  absence  of  fibrinogen  and  the  presence  of  a 
little  fibrin  globulin  and  an  abundance  of  fibrin  ferment.  Consid- 
ered qualitatively  the  blood-serum  contains  the  same  chief  con- 
stituents as  the  blood-plasma. 

If  undiluted  serum  be  sufficiently  acidified  with  acetic  acid,  a  precipitate  is 
obtained  cousisling  of  partly  unchanged  serum  globulin,  fibrin  globulin,  leci- 
thin, and,  in  some  cases,  coloring  matters  (bile  coloring  matters  in  the  serum 
of  the  horse).  By  the  same  process  Wooldridge  precipitated  from  the 
blood-serum  of  the  sheep  and  dog  a  substance  which  is  closely  related  to 
fibrinogen  and  was  called  by  him  '•  serum  fibrinogen." 

Blood-serum  is  a  sticky  liquid  which  is  more  alkaline  than  the 
plasma.  The  specific  gravity  in  man  is  1.027  to  1.032,  average  1.028 
The  color  is  strongly  or  faintly  yellow;  in  human  blood-serum  it  is 
pale  yellow  with  a  shade  towards  green,  and  in  horses  it  is  often 
amber-yellow.  The  serum  is  ordinarily  clear;  after  a  meal  it  may 
be  opalescent,  cloudy,  or  milky-white,  according  to  the  amount  of 
fat  contained  in  the  food. 

Besides  the  above-mentioned  bodies,  the  following  constituents 
are  found  in  the  blood-plasma  or  blood-serum : 

Fat  occurs  from  1-7  p.  m.  in  fasting  animals.  After  partaking 
of  food  the  amount  is  increased,  and  if  the  food  is  rich  in  fat  as 
much  as  12.5  p.  m.  has  been  found  in  the  blood  of  dogs  (Eohrig). 
We  also  find  soaps  (Hoppe-Seyler),  cJiolesterin,  and  lecithin. 

Glucose  seems  to  be  a  physiological  constituent  of  the  plasma. 
According  to  the  investigations  of  Abbles,  Ewald,  Kulz,  and 
Seegen,  the  sugar  found  in  the  plasma  is  glucose.  Otto  found  in 
the  plasma,  besides  glucose,  another  reducing,  non-fermentable  sub- 
stance.    The  amount  of  glucose  in  the  blood  is  about  1-1.5  p.  m. 


THE  BLOOD.  63 

Otto  found  in  human  blood  1.18  p.  m.  glucose  and  0.29  p.  m.  of  the 
other  reducing  substance.  The  amount  of  glucose  in  the  blood 
geems  to  be  almost  independent  of  the  food;  nevertheless  after 
feeding  with  large  quantities  of  glucose  and  dextrin  Bleile  ob- 
served a  significant  increase  of  glucose.  If  the  amount  is  more 
than  3  p.  m.,  according  to  Cl.  Bernakd,  the  glucose  passes  into 
the  urine,  producing  glycosuria.  The  different  amounts  of  glucose 
in  the  blood  from  different  vessels  and  under  various  conditions 
will  be  fully  discussed  later. 

Among  the  bodies  which  are  found  in  the  blood  and  without 
doubt  met  with  in  smaller  or  greater  amounts  in  the  plasma  are  to 
be  mentioned  urea,  uric  acid  (found  in  human  blood  by  Abeles), 
creatin,  carhatnic  acid,  par alaciic  acid,  and  hijjpuric  acid.  Under 
pathological  conditions  the  following  have  been  found :  hypoxan- 
tMn,  leucin,  tyrosin,  and  hiliary  constituents. 

The  coloring  matters  of  the  blood-serum  are  very  little  known. 
In  equine  blood-serum  biliary  coloring  matters,  bilirubin,  besides 
other  coloring  matters,  occur.  The  yellow  coloring  matter  of  the 
serum  seems  to  belong  to  the  group  of  luteins,  which  are  often  called 
lipochromes  or  fat-coloring  matters.  From  ox-serum  Krukenberg 
was  able  to  isolate  with  amyl  alcohol  a  so-called  lipochrome  whose 
solution  shoAvs  two  absorption-bands,  of  which  one  encloses  the  line 
F  and  the  other  lies  between  i^and  G.  Halliburton  found  in 
the  blood  of  birds  and  amphibia  a  yellow  coloring  matter  which 
only  showed  one  absorption-band. 

The  mineral  bodies  in  serum  and  plasma  are  qualitatively,  but 
not  quantitatively,  the  same.  A  part  of  the  calcium,  magnesium, 
and  phosphoric  acid  is  removed  on  the  coagulation  of  the  fibrin.  By 
means  of  dialysis,  the  presence  of  sodium  chloride,  which  forms  the 
chief  mass  or  60-70^  of  the  total  mineral  bodies,  also  lime  salts, 
sodium  carbonate,  besides  traces  of  sulphuric  and  phosphoric 
acids  and  potassium,  may  be  shown  in  the  serum.  Traces  of  silicic 
acid,  fluorine,  copper,  iron,  manganese,  and  ammonia  are  claimed 
to  have  been  found  in  the  serum.  As  in  most  animal  fluids,  the 
chlorine  and  sodium  are  in  the  blood-serum  in  excess  of  the  phos- 
phoric acid  and  potassium  (the  occurrence  of  which  in  the  serum 
is  even  doubted).  The  acids  found  in  the  ash  are  not  sufficient  to 
saturate  the  bases  found,  a  condition  which  shows  that  a  part  of 
the  bases  is  combined  with  organic  substances,  perhaps  albumin. 


64 


PHTSIOLOGICAL   CHEMISTRY. 


The  gases  of  the  blood-serum,  which  consist  chiefly  of  carbon 
dioxide  with  only  a  little  nitrogen  and  oxygen,  will  be  described 
when  treating  of  the  gases  of  the  blood. 

Because  of  the  difficulty  of  obtaining  plasma  only  a  few  analy- 
ses haye  been  made.  As  an  example  the  results  of  the  analyses  of 
the  blood-plasma  of  the  horse  will  be  given  below.  The  analysis 
No.  1  was  made  by  Hoppe-Setlee.  No.  2  is  the  average  of  the 
results  of  three  analyses  made  by  the  author.  The  figures  are 
given  in  1000  parts  of  the  plasma. 

No.  1.  No.  2. 

Water 908.4  917.6 

Solids 91.6  82.4 

Total  albuminous  bodies 77.6  69.5 

Fibrin 10.1  6.5 

Globulin 38.4 

Serum  albumin 24.6 

Fat 1.2  1 

Extractive  substances 4.0  I  ^o  q 

Soluble  salts 6.4  |  ^"^'^ 

Insoluble  salts 1-7  J 

As  an  example  of  the  constitution  of  the  blood-serum  with 
special  regard  to  the  relationship  of  the  different  albuminous 
bodies  to  each  other,  the  following  analyses  are  given.  The  results 
are  in  1000  parts. 


Serum 

Solids. 

Total 
Albumin- 
ous 
Bodies. 

Serum 
Globulin 

Serum 
Albumin. 

Lecithin, 

Fat, 
Salts,  etc. 

Serum 
Globulin. 

Authority. 

from 

Serum 
Albumin 

Man 

92.07 

76.20 

31.04 

45.16 

15.88 

1 
1.5 

Hammaksten 

Horse . . 

85.97 

72.57 

45.65 

26.92 

13.40 

1 
0.591 

" 

Ox 

89.65 

74.99 

41.69 

33.30 

14.66 

1 

0.842 

<( 

Dog. . . . 

58.20 

20.50 

37.70 

1 

1.8 

Sertoli 

Hen.... 

54.00 

39.49 

7.84 

31.65 

14.51 

1 
4.03 

Hammaksten 

Frog... 

25.40 

21.80 

8.60 

1 
0.165 

Halliburtok 

Eel 

67.30 

52.80 

14.50 

1 

0.275 

THE  BLOOD.  65 

According  to  Hallibueton,  the  amount  of  the  albumins  in 
comparison  with  the  globulins  in  cold-blooded  animals  is  not  only 
proportionally  smaller,  but  the  total  amount  of  albuminous  bodies 
is  smaller  than  in  the  warm-blooded  animals. 

By  a  comparative  investigation  of  serum  and  plasma  from  the 
same  individual,  we  find  more  serum  globulin  in  the  one  than  in 
the  other.  The  reason  for  this  may  lie  partly  in  the  fact  that  in 
the  coagulation  of  fibrin  from  the  fibrinogen  some  fibrin  globulin  is 
formed  which  in  the  quantitative  estimation  is  precipitated  with  the 
serum  globulin,  and  partly  because  the  white  corpuscles  yield  serum 
globulin  in  the  fibrin  coagulation  (Alex.  Schmidt). 

The  quantity  of  mineral  bodies  in  tlie  serum  has  been  determined 
by  many  investigators. 

The  conclusion  drawn  from  the  analyses  is  that  there  exists  a 
rather  close  correspondence  between  human  and  animal  blood-senim, 
and  it  is  therefore  sufficient  to  give  here  the  analysis  of  C.  Schmidt 
of  (1)  human  blood,  and  of  (2)  pig-  and  (3)  ox-blood  by  Buxge. 
As  in  the  calcination  of  lecithin  and  albumins  incorrect  results 
are  obtained  for  the  phosphoric  and  sulphuric  acids,  these  result 
will  not  be  given  below.  All  figures  correspond  to  1000  parts  of 
serum. 

12  3 

KaO 0.392  0.273  0.254 

NaaO 4.463  4.272  4.351 

CI 3.612  3.611  3.717 

CaO 0.163  0.136  0.126 

MgO 0.101  0.038  0.045 

The  amount  of  NaCl  is  6-7  p.  m.,  and  it  is  remarkable  that  this 
amount  of  NaCl  remains  almost  constant,  so  that  with  food  con- 
taining an  excess  of  NaCl  it  is  quickly  eliminated  by  the  urine,, 
and  with  food  poor  in  chlorides  the  amount  in  the  blood  fijst 
decreases,  but  increases  after  taking  chlorides  from  the  tissues. 
The  secretion  of  chlorides  by  the  urine  is  thereby  diminished. 

The  amount  of  phosphoric  acid,  calculated  as  Na^HPO^ ,  in  the 
serum  freed  from  lecithin  has  been  determined  as  0.02-0.09  p.  m. 
by  Sertoli  and  Mroczkowski  in  different  varieties  of  serum.  The 
small  amount  of  iron  sometimes  found  in  the  serum  probably  origi- 
nates from  a  contamination  with  the  blood-coloring  matters. 


66  PHYSIOLOGICAL   CHEMISTBT. 

II.  The  Form-elements  of  the  Blood. 
The  Red  Blood-corpuscles. 

The  blood-corpuscles  are  round,  biconcave  disks  without  mem- 
brane and  nucleus  in  man  and  mammalia  (with  the  exception  of 
the  llama,  the  camel,  and  their  congeners).  In  the  latter  animals, 
as  also  in  birds,  amphibia,  and  fishes  (with  the  exception  of 
the  cyclostoma),  the  corpuscles  have  in  general  a  nucleus,  are 
biconvex  and  more  or  less  elliptical.  The  size  varies  in  differ- 
ent animals.  In  man  they  have  an  average  diameter  of  7 
to  8  fA.  (m  =  0.001  m.m.)  and  a  maximum  thickness  of  1.9  yw. 
Their  specific  gravity  is  1.088  to  1.089  (0.  Schmidt)  or  1.105 
(Welcker).  They  are  heavier  than  the  blood-plasma  or  serum, 
and  therefore  sink  in  these  liquids.  In  the  discharged  blood  they 
may  lie  sometimes  with  their  fiat  surfaces  together,  forming  a 
cylinder  like  a  roll  of  coin.  The  reason  for  this  is  unknown,  but 
as  it  may  be  observed  in  defibrinated  blood  it  seems  probable  that 
the  formation  of  fibrin  has  nothing  to  do  with  it.  Seen  with  the 
microscope,  each  blood-corpuscle  has  a  pale  yellow  color,  and  only 
in  moderately  thick  layers  is  the  color  somewhat  reddish. 

The  number  of  red  blood-corpuscles  is  different  in  the  blood  of 
various  animals.  In  the  blood  of  man  there  are  generally  5  million 
red  corpuscles  in  1  c.mm.,  and  in  woman  4  to  4.5  million. 

On  diluting  the  blood  with  water  and  alternately  freezing  and 
thawing  it,  as  also  on  shaking  it  with  ether,  or  by  the  action  of 
chloroform  or  bile,  a  remarkable  change  takes  place.  The  blood- 
coloring  matters,  which  are  hardly  free  in  the  blood-corpuscles,  but 
rather,  according  to  the  view  of  Hoppe-Setlee,  are  combined 
with  some  other  substance,  perhaps  lecithin,  are  by  this  means 
set  free  from  these  combinations  and  pass  into  solution,  while 
the  remainder  of  each  blood-corpuscle  forms  a  swollen  mass. 
By  the  action  of  carbon  dioxide,  by  the  careful  addition  of  acids, 
acid  salts,  tincture  of  iodine,  or  certain  other  bodies,  this  residue, 
rich  in  albumin,  condenses  and  in  many  cases  the  form  of  the 
blood-corpuscles  may  be  again  obtained.  This  residue  has  been 
called  the  stroma  of  the  red  blood -corpuscles. 


THE  BLOOD.  67 

To  isolate  the  stromata  of  the  blood-corpuscles  they  are  washed 
first  by  diluting  the  blood  with  10-20  vols,  of  a  1-2^  common-salt 
solution  and  then  separating  the  mixture  by  centrifugal  force  or 
by  allowing  it  to  stand  at  a  low  temperature.  This  is  repeated  a 
few  times  until  the  blood-corpuscles  are  freed  from  serum.  These 
purified  blood-corpuscles  are,  according  to  Wooldkidge,  mixed 
with  5-6  vols,  of  water  and  then  a  little  ether  is  added  until  com- 
plete solution  is  obtained.  The  leucocytes  gradually  settle  to  the 
bottom,  a  movement  which  may  be  accelerated  by  centrifugal  force, 
and  the  liquid  which  separates  therefrom  is  very  carefully  treated 
with  a  1^  solution  of  KHSO^  until  it  is  about  as  dense  as  the 
original  blood.  The  separated  stromata  is  collected  on  a  filter  and 
quickly  washed. 

WooLDEiDGE  found  as  constituents  of  the  stroma  lecithin, 
clioJesterin,  and  a  glohulin  which,  according  to  Halliburton,  is 
the  above-mentioned  (page  58)  fibrinoplastic  acting  cell-globulin. 
Nucleo-albumin  and  albumoses  could  not  be  detected  (Halli- 
BURTOx).  The  nucleated  red  blood-corpuscles  of  the  bird  con- 
tain, according  to  Plos'z  and  Hoppe-Seyler,  nuclein  and  an  al- 
buminous body  which  swells  to  a  slimy  mass  in  a  10^  common-salt 
solution  and  which  seems  to  be  closely  related  to  the  hyaline  sub- 
stance {hyaline  substance  of  Eoyida)  occurring  in  the  lymph-cells. 
The  red  blood-corpuscles  without  any  nucleus  are,  as  a  rule,  very 
poor  in  albumin  but  are  rich  in  haemoglobin;  the  nucleated  cor- 
puscles are  richer  in  albumin  and  poorer  in  haemoglobin. 

A  gelatinous,  albuminous,  fibrin-like  body  may  be  obtained  from 
the  red  blood-corpuscles.  This  fibrin-like  mass  has  been  observed 
on  freezing  and  then  thawing  the  sediment  of  the  blood-corpuscles, 
or  on  discharging  the  spark  from  a  large  Leyden  jar  through  the 
blood,  or  on  dissolving  the  blood-corpuscles  of  one  kind  of  ani- 
mal in  the  serum  of  another  (Laxdois,  stroma  fibrin).  In  none 
of  these  cases  has  it  been  shown  that  we  have  to  deal  with  a  fibrin 
formation  at  the  expense  of  the  stroma.  It  seems  only  to  have 
been  shown  that  the  red  blood-corpuscles  of  frog's  blood  contain 
fibrinogen  (Alex.  Schmidt  and  Semmee). 

Tlie  mineral  bodies  of  the  red  corpuscles  are  chiefly  potassium, 
phosphoric  acid,  and  chlorine ;  in  the  red  corpuscles  of  man,  dog, 
and  the  ox  sodium  has  also  been  found. 


68  PHYSIOLOGICAL   CEEMI8TRT. 

The  most  important  constituent  of  the  blood-corpuscles  from  a 
physiological  standpoint  is  the  red  coloring  matter. 

Blood-coloring  Matters. 

According  to  Hoppe-Setlek  the  coloring  matter  of  the  red 
blood-corpuscles  is  not  in  a  free  state  but  combined  with  some 
other  substance.  The  crystalline  coloring  matter,  the  haemo- 
globin or  oxyhgemoglobin,  which  may  be  isolated  from  the  blood,  is 
considered,  according  to  Hoppe-Seyler,  as  a  splitting  product  of 
this  combination,  and  it  acts  in  many  ways  like  the  questionable 
combination  itself.  This  combination  is  insoluble  in  water  and 
uncrystallizable.  It  strongly  decomposes  hydrogen  peroxide  with- 
out being  oxidized  itself;  it  shows  a  greater  resistance  to  certain 
chemical  reagents  (as  potassium  ferricyanide)  than  the  free  color- 
ing matter,  and  lastly  it  gives  off  its  loosely-combined  oxygen  much 
more  easily  in  vacuum  than  the  free  coloring  matter.  To  dis- 
tinguish between  the  splitting  products,  the  hsemoglobin  and  the 
oxyhaemoglobin,  we  may  call  the  combination  of  the  blood -coloring 
matter  of  the  venous  blood-corpuscles  plileMn,  and  that  of  the  arte- 
rial arterin  (Hoppe-Setler).  Since  the  above-mentioned  combi- 
nation of  the  blood-coloring  matters  with  other  bodies,  for  example 
(if  they  really  do  exist)  with  lecithin,  have  not  been  closely  studied, 
the  following  statements  will  only  apply  to  the  free  coloring  matter, 
the  haemoglobin. 

The  color  of  the  blood  depends  in  part  on  hcemoglobin  and  in 
part  on  a  molecular  combination  of  this  with  oxygen,  the  oxyhcBmo- 
glohin.  We  find  in  blood  after  suffocation  almost  exclusively  hemo- 
globin, in  arterial  blood  disproportionately  large  amounts  of  oxyhae- 
moglobin, and  in  venous  blood  a  mixture  of  both.  Blood-coloring 
matters  are  found  also  in  striated  as  well  as  in  certain  smooth  mus- 
cles, and  lastly  in  solution  in  different  invertebrata.  The  quantity  of 
haemoglobin  in  human  blood  may  indeed  be  somewhat  variable  under 
different  circumstances,  but  amounts  averaging  about  14^  or  8.5 
grammes  have  been  determined  for  each  kilo  of  the  weight  of  the 
body. 

The  haemoglobin  belongs  to  the  group  of  proteids,  and  yields  as 
splitting  products,  besides  very  small  amounts  of  volatile  fatty  acids 


THE  BLOOD. 


69 


and  other  bodies,  chiefly  alhumin  (96^),  and  a  coloring  matter, 
hmmochromogen  (4^),  containing  iron,  which  in  the  presence  of 
oxygen  is  easily  oxidized  into  hmmatin. 

The  haemoglobin  prepared  from  different  kinds  of  blood  has 
not  exactly  the  same  constitution,  which  seems  to  indicate  the  pres- 
ence of  different  haemoglobins.  The  analyses  of  different  investi- 
gators of  the  haemoglobin  from  the  same  kind  of  blood  do  not 
always  agree  with  one  another,  which  probably  depends  upon  the 
somewhat  various  methods  of  preparation.  The  following  analyses 
are  given  as  examples  of  the  constitution  of  different  haemoglobins : 

Haemoglobin  c  H         N          S         Fe  O  P,Os 

from  the 

Dog 53.85  7.32  16.17  0.390  0.430  21.84  (Hoppe-Seyler.) 

•'    54.57  7.22  16.38  0  568  0.336  20.93  . .  .  .  (Jaquet.) 

Horse 54.87  6.97  17.31  0.650  0.470  19.73  (Kossel.) 

'■     51.15  6.76  17.94  0.390  0.335  23.43  (Zinoffsky.) 

Ox 54.66  7.25  17.70  0.477  0.400  19.543  (Hufmer.) 

Pig 54.17  7.38  16.23  0.660  0.430  21.360  ....(Otto.) 

"    54.71  7.38  17.43  0.479  0.399  19.602  (Hdfner.) 

Guinea-pig  54.12  7.36  16.78  0.580  0.480  20.680  (Hoppe-Seyler.) 

Squirrel...  54.09  7.39  16.09  0.400  0.590  21.440  

Goose 54.26  7.10  16.21  0.590  0.430  20,690  0.77 

Hen 52.47  7.19  16.45  0.857  0.335  22.500  0.197  (Jacquet.). 

The  question  whether  the  amount  of  phosphorus  in  the  haemo- 
globin from  birds  exists  as  a  contamination  or  as  a  constituent  has 
not  been  decided.  In  the  haemoglobin  from  the  horse  (Zinoffsky), 
the  pig,  and  the  ox  (Hufxer)  we  have  1  atom  of  iron  to  2  atoms  of 
sulphur,  while  in  the  hsemoglobin  from  the  dog  (Jacquet)  the  rela- 
tion is  1  to  3.  From  the  data  of  the  elementary  analysis,  as  also  from 
the  amount  of  loosely-combined  oxygen,  Hufjster  has  calculated 
the  molecular  weight  of  dog-haemoglobin  as  14,129  and  the  formula 
C^jHi.j.Njj.FeSjOjg,.  The  molecular  weight  is  therefore  very  high. 
The  hgemoglobin  from  various  kinds  of  blood  not  only  show  a 
diverse  constitution,  but  also  a  different  solubility  and  crystalline 
form,  and  a  varying  quantity  of  water  of  crystallization,  from  which 
we  infer  that  there  are  several  kinds  of  haemoglobin. 

Oxyhaemoglobin,  which  has  also  been  called  H^matoglobulin 
or  H^MATOCRYSTALLIN,  is  a  molecular  combination  of  haemoglobin 
and  oxygen.  For  each  molecule  of  haemoglobin  1  molecule  of  oxy- 
gen exists;  and  the  amount  of  loosely-combined  oxygen  which  is 
united  to  1  grm.  oxyhaemoglobin  (of  the  dog)  has  been  determined  by 


70  PHYSIOLOGICAL  CHEMI8TRT. 

HiJFNER  as  1.582  c.  c.  (at  0°  C.  and  760  in.in.  Hg).  The  abilitj 
of  haemoglobin  to  take  up  oxygen  seems  to  be  a  function  of  the  iron 
it  contains,  and  when  this  is  calculated  as  about  0.33-0.40^,  then 
1  atom  of  iron  in  the  haemoglobin  corresponds  to  about  3  atoms  ■=  1 
molecule  of  oxygen.  The  combination  of  hsemoglobin  with  oxygen 
is,  as  has  been  stated,  loose  and  dissociatable,  and  the  quantity 
of  oxygen  taken  up  by  a  hsemoglobin  solution  depends  upon  the 
pressure  of  the  oxygen  at  that  temperature.  If  this  latter  be 
decreased  by  means  of  a  vacuum,  especially  on  gently  heating  or 
by  passing  some  indifferent  gas  through  the  solution,  all  of  the 
oxygen  may  be  expelled  from  an  oxyhaemoglobin  solution  so  that 
only  haemoglobin  remains.  The  reverse  of  this  is  true  of  a  haemo- 
globin solution  which  by  its  remarkable  attraction  for  oxygen  may 
be  converted  into  oxyhaemoglobin.  Oxyhaemoglobin  is  generally 
considered  as  a  weak  acid. 

Oxyhaemoglobin  has  been  obtained  in  crystals  from  several 
varieties  of  blood.  These  crystals,  first  observed  by  Reichert 
and  FuNKE,  are  blood-red,  transparent,  silky,  and  may  be  2-3  m.m, 
long.  The  oxyhsemoglobin  from  squirrel's  blood  crystallizes  in  six- 
sided  plates  of  the  hexagonal  system;  the  other  varieties  of  blood 
yield  needles,  prisms,  tetrahedra,  or  plates  which  belong  to  the 
rhombic  system.  The  quantity  of  water  of  crystallization  varies 
between  3-10^  for  the  different  oxyhaemoglobin  s.  When  com- 
pletely dried  at  a  low  temperature  over  sulphuric  acid  the  crys- 
tals may  be  heated  to  110°-115°  C.  without  decomposing.  At 
higher  temperatures,  somewhat  above  160°  C,  they  decompose, 
giving  an  odor  of  burnt  horn,  and  leave,  after  complete  combus- 
tion, an  ash  consisting  of  oxide  of  iron.  The  oxyhaemoglobin 
crystals  from  difficultly-crystallizable  kinds  of  blood,  for  exam- 
ple from  such  as  ox's,  human,  and  pig's  blood,  are  easily  soluble  in 
water.  The  oxyhsemoglobin  from  easily- crystallizable  blood,  as 
from  that  of  the  horse,  dog,  squirrel,  and  guinea-pig,  are  soluble 
with  difficulty  in  the  order  above  given.  The  oxyhaemoglobin 
dissolves  more  easily  in  a  very  dilute  solution  of  alkali  carbonate 
than  in  pure  water,  and  this  solution  may  be  kept.  The  presence 
of  a  little  too  much  alkali  causes  the  oxyhaemoglobin  to  quickly 
decompose.  The  crystals  are  insoluble  without  decolorization 
in    absolute    alcohol.      According    to    Nencki,    it    is    converted 


THE  BLOOD.  71 

into  an  isomeric  or  polymeric  modification,  called  by  him  pardJicBmo^ 
glohin.  Oxyhemoglobin  is  insoluble  in  ether,  chloroform,  benzol, 
and  carbon  disulphide. 

A  solution  of  oxyhsemoglobin  in  water  is  not  precipitated  by 
many  metallic  salts,  but  is  precipitated  by  sugar  of  lead.  On  heat- 
ing the  watery  solution  it  decomposes  at  60°  to  70°  C,  and  it  splits 
off  albumin  and  haematin.  It  is  also  decomposed  by  acids,  alkalies, 
and  many  metallic  salts.  It  gives  the  ordinary  reactions  for  albu- 
min with  the  albumin  reagents  which  first  decompose  the  oxy haemo- 
globin with  the  splitting  off  of  albumin. 

The  oxyhaemoglobin  may,  when  it  is  gradually  oxidized,  act  as 
an  "  ozone  exciter  "  by  the  disjoining  of  neutral  oxygen,  making  the 
oxygen  active  (Pfluger).  It  may  also  have  another  relation  to 
ozone,  since  it  has  the  property  of  an  "  ozone  transmitter  "  in  that 
it  causes  the  reaction  of  certain  reagents  (turpentine)  containing 
ozone  upon  ozone  reagents  such  as  tincture  of  guaiacum  (Schok- 
BEIN,  His).  According  to  Kowalewskt,  it  is  not  ozone  but  an 
oxidation-product  of  turpentine  that  we  have  to  deal  with;  but  this 
question  requires  further  proof. 

A  sufficiently  dilute  solution  of  oxyhaemoglobin  or  arterial  blood 
shows  a  spectrum  with  two  absorption-bands  between  the  Frauk- 
HOFER  lines  D  and  E.  The  one  band  a,  which  is  narrower  but 
darker  and  sharper,  lies  on  the  line  D;  the  other,  broader,  less  de- 
fined and  less  dark  band  ft,  lies  at  E.  These  bands  can  be  detected 
in  a  layer  of  1  cm.  of  a  0.1  p.  m.  solution  of  oxyhemoglobin.  In  a 
still  weaker  dilution  the  band  ^  first  disappears.  By  increased  con- 
centration of  the  solution  the  two  bands  become  broader,  the  space 
between  them  smaller  or  entirely  obliterated,  and  at  the  same  time  the 
blue  and  violet  part  of  the  spectrum  is  darkened.  The  oxyhaemo- 
globin may  be  differentiated  from  other  coloring  matters  having  a 
similar  absorption-spectrum  by  its  behavior  towards  reducing  sub- 
stances.    (See  below.) 

A  great  many  methods  have  been  proposed  for  the  preparation 
of  oxyhaemoglobin  crystals,  but  in  their  chief  features  they  all  agree 
with  the  following  method  as  suggested  by  Hoppe-Seyler  :  The 
washed  blood-corpuscles  (best  those  from  the  dog  or  the  horse)  are 
stirred  with  2  vols,  water  and  then  shaken  with  ether.  After 
decanting  the  ether  and  allowing  tlie  ether  which  is  retained  by 


73  PHYSIOLOGICAL   CHEMISTRY. 

the  blood  solution  to  evaporate  in  an  open  dish  in  the  air,  cool  the 
filtered  blood  solution  to  0°  Q.,  add  while  stirring  \  vol.  of  alcohol 
also  cooled,  and  allow  to  stand  a  few  days  at  —  5°  to  —  10°  C. 
The  crystals  which  separate  may  be  repeatedly  recrystallized  by  dis- 
solving in  water  of  about  35°  C,  cooling  and  adding  cooled  alcohol 
as  above.  Lastly,  they  are  washed  with  cooled  water  containing 
alcohol  (i  vol.  alcohol)  and  dried  in  vacuum  at  0°  C.  or  a  lower 
temperature.  According  to  GscheIdlen^s  investigations,  oxy- 
hsemoglobin  crystals  may  be  obtained  from  difficulty  crystallizable 
varieties  of  blood  by  allowing  the  blood  first  to  putrify  slightly 
in  sealed  tubes.  After  shaking  with  air  by  which  the  blood  is 
again  arterialized,  proceed  as  above. 

For  the  preparation  of  oxyhgemogiobin  crystals  in  small  quanti- 
ties from  blood  easily  crystallized,  it  is  often  sufficient  to  stir  a 
drop  of  blood  with  a  little  water  on  a  microscope  slide  and  allow  the 
mixture  to  evaporate  so  that  the  drop  is  surrounded  by  a  dried  ring. 
After  covering  with  a  thin  glass,  the  crystals  gradually  appear  radiat- 
ing from  the  ring.  These  crystals  are  formed  in  a  surer  manner  if 
the  blood  is  first  mixed  with  some  water  in  a  test-tube  and  shaken 
with  ether  and  a  drop  of  the  lower  deep-colored  liquid  treated  as 
above  on  the  slide. 

Haemoglobin,  also  called  Eeduced  Hemoglobin  or  Purple 
Cruorin  (Stokes),  occurs  only  in  very  small  quantities  in  arterial 
blood,  in  larger  quantities  in  venous  blood,  and  is  nearly  the  only 
blood-coloring  matter  after  suffocation. 

Haemoglobin  is  much  more  soluble  than  the  oxyhaemoglobin,  and 
it  can  therefore  only  be  obtained  as  crystals  with  difficulty.  These 
crystals  are  as  a  rule  isomorphous  to  the  corresponding  oxyhgemo- 
giobin crystals,  but  are  darker,  having  a  shade  towards  the  blue  or 
purple,  and  are  decidedly  more  pleochromatic.  Its  solutions  in 
water  are  darker  and  more  violet  or  purplish  than  solutions  of  oxy- 
hsemoglobin  of  the  same  concentration.  They  absorb  the  blue  and 
the  violet  rays  of  the  spectrum  in  a  less  marked  degree,  but  strongly 
absorb  the  rays  lying  between  C  and  D.  In  proper  dilution  the 
solution  shows  a  spectrum  with  one  broad,  not  sharply-defined  band 
between  D  and  E.  This  band  does  not  lie  in  the  middle  between 
D  and  E,  but  is  towards  the  red  end  of  the  spectrum,  a  little  over 
the  line  D.  A  haemoglobin  solution  actively  absorbs  oxygen  from 
the  air  and  is  converted  into  an  oxyhemoglobin  solution. 

A  solution  of  oxyhaemoglobin  may  be  easily  converted  into  a 
hsemoglobin  solution  by  means  of  a  vacuum,  by  passing  an  indiffer- 


THE  BLOOD  73 

ent  gas  through,  or  by  the  addition  of  a  reducing  substance,  as,  for 
example,  an  ammoniacal  ferrotartrate  solution  (Stokes'  reduction- 
liquid).  If  an  oxyhaemoglobin  solution  or  arterial  blood  is  kept 
in  a  sealed  tube,  we  observe  a  gradual  reduction  of  the  oxyhaemo- 
globin into  haemoglobin.  If  the  solution  has  a  proper  concentration, 
a  crystallization  of  haemoglobin  may  occur  in  the  tube  at  lower 
temperatures  (Huener). 

Carbon  Monoxide  Haemoglobin  is  the  molecular  combination  be- 
tween 1  mol.  hsemoglobin  and  1  mol.  CO.  This  combination  is 
stronger  than  the  oxygen  combination  of  haemoglobin.  The  oxygen 
is  for  this  reason  easily  driven  off  by  carbon  monoxide,  and  this  ex- 
plains the  poisonous  action  of  carbon  monoxide,  which  kills  by  the 
expulsion  of  the  oxygen  of  the  blood. 

Carbon  monoxide  haemoglobin  is  formed  by  saturating  blood  or 
a  haemoglobin  solution  with  carbon  monoxide,  and  may  be  obtained 
as  crystals  by  the  same  means  as  oxyhsemoglobin.  These  crystals 
^re  isomorphous  to  the  oxyhaemoglobin  crystals,  but  are  less  soluble, 
more  constant,  and  their  bluish-red  color  is  more  marked.  For  the 
detection  of  carbon  monoxide  hemoglobin  its  absorption  spectrum 
is  of  the  greatest  importance.  This  spectrum  shows  two  bands  which 
are  very  similar  to  those  of  oxyhaemoglobin,  but  they  occur  more 
towards  the  violet  part  of  the  spectrum.  These  bands  do  not  change 
noticeably  on  the  addition  of  reducing  substances;  this  constitutes 
an  important  difference  between  carbon  monoxide  and  oxyhaemo- 
globin. If  the  blood  contains  oxyhaemoglobin  and  carbon  monoxide 
haemoglobin  at  the  same  time,  we  will  obtain  on  the  addition  of  a 
reducing  substance  (ammoniacal  ferrotartrate  solution)  a  mixed 
spectrum  originating  from  the  haemoglobin  and  carbon  monoxide 
haemoglobin. 

A  great  many  reactions  have  been  suggested  for  the  testing  of 
carbon-monoxide  haemoglobin  in  medico-legal  cases.  A  simple 
and  at  the  same  time  a  good  one  is  Hoppe-Seyler's  soda  test. 
The  blood  is  treated  with  double  its  volume  of  caustic-soda  solution 
of  1.3  sp.  gr,,  by  which  ordinary  blood  is  converted  into  a  dingy 
brownish  mass,  which  when  spread  out  on  porcelain  is  brown 
with  a  shade  of  green.  Carbon-monoxide  blood  gives  under  the 
same  conditions  a  red  mass,  which  if  spread  out  on  porcelain 
shows  a  beautiful  red  color.  Several  modifications  of  this  test  have 
been  proposed. 


74  PHT8I0L00IGAL   CHEMISTBT. 

Nitric -oxide  Haemoglobiii  is  also  a  crystalline  molecular  com- 
bination which  is  even  stronger  than  the  carbon-monoxide  haemo- 
globin. Its  solution  shows  two  absorption-bands  which  are  paler 
and  less  sharp  than  the  carbon-monoxide  hasmoglobin  bands,  and 
they  disappear  on  the  addition  of  reducing  bodies. 

Haemoglobin  forms  also  a  molecular  combination  with  acetylene.  It  is  also 
claimed  that  it  forms  a  combination  with  liydrocyanic  acid. 

Carbon  -  dioxide  Haemoglobin.  Haemoglobin  forms  a  molecular 
combination  with  carbon  dioxide  whose  spectrum  is  similar  to  that 
of  haemoglobin  (Torup).  By  the  action  of  carbon  dioxide  on 
haemoglobin  part  of  the  latter  is  decomposed  with  the  separation  of 
albumin  (Bohe,  Toeup),  and  the  combination  seems  to  be  rather 
carbon-dioxide  haemochromogen  (see  below  :  Haemochromogen). 

Methsemoglobin.  This  name  has  been  given  to  a  coloring  matter 
which  is  easily  obtained  from  the  oxyhaemoglobin  as  a  transforma- 
tion product  and  which  has  been  correspondingly  found  in  transuda- 
tions and  cystin  fluids  containing  blood,  in  urine,  in  haematuria  or 
hasmoglobinuria,  also  in  urine  and  blood  on  poisoning  with  potas- 
sium chlorate,  amyl  nitrite  or  alkali  nitrite,  and  many  other 
bodies. 

Methaemoglobin  does  not  contain  any  oxygen  in  molecular  or 
dissociable  combination,  but  still  the  oxygen  seems  to  be  of  im- 
portance in  the  formation  of  methaemoglobin.  If  arterial  blood  be 
sealed  up  in  a  tube,  it  gradually  consumes  its  oxygen  and  becomes 
venous,  and  by  this  absorption  of  oxygen  a  little  methaemoglobin  is 
formed.  The  same  occurs  on  the  addition  of,  a  small  quantity  of 
acid  to  the  blood.  By  the  spontaneous  decomposition  of  blood 
some  methaemoglobin  is  formed,  and  by  the  action  of  ozone,  potas- 
sium permanganate,  potassium  ferricyanide,  and  certain  other 
bodies  on  the  blood  an  abundant  formation  of  methaemoglobin 
takes  place. 

According  to  a  few  investigators,  among  others  Soebt  and 
Jadeeholm,  the  methaemoglobin  contains  more  oxygen  than 
oxyhaemoglobin,  while  according  to  others,  among  whom  may  be 
mentioned  Hoppe-Sbtlee,  it  contains  less.  Hufnee  and  Otto 
claim  that  it  contains  just  as  much  oxygen,  but  that  it  is  more 
strongly  combined.    Jadeeholm    and    Saaebach  claim  that  a 


THE  BLOOD.  75 

methaemoglobin  is  first  converted  into  an  oxyhaemoglobin  and  then 
into  a  haemoglobin  sohition  by  reducing  substances,  while  Hoppe- 
Setler  claims  that  it  is  converted  directly  into  a  haemoglobin 
solution. 

Methaemoglobin  has  the  same  constitution  as  oxyhaemoglobin 
(HuFXER  and  Otto).  It  was  first  shown  by  them  that  it  crystal- 
lizes in  brownish-red  needles,  prisms,  or  six-sided  plates.  It  dissolves 
easily  in  water  ;  the  solution  has  a  brown,  color  and  becomes  a 
beautiful  red  on  the  addition  of  alkali.  The  solution  of  the  pure 
substance  is  not  precipitated  by  lead  acetate  alone,  but  by  lead 
acetate  and  ammonia.  The  absorption-spectrum  of  a  watery  or 
acidified  solution  of  methaemoglobin  is  very  similar  to  that  of 
haematin  in  acid  solution,  but  is  easily  distinguished  from  the 
latter  since,  on  the  addition  of  a  little  alkali  and  a  reducing 
substance,  the  former-  passes  over  to  the  spectrum  of  reduced 
haemoglobin,  while  a  haematin  solution  under  the  same  conditions 
gives  the  spectrum  of  an  alkaline  haemochromogen  solution  (see 
below).  Methaemoglobin  in  alkaline  solution  shows  two  absorption- 
bands  which  are  like  the  two  oxyhaemoglobin  bands,  but  they  differ 
from  these  in  that  the  band  ft  is  stronger  than  a.  By  the  side  of 
the  band  a  and  united  with  it  by  a  shadow  lies  a  third,  fainter 
band  between  C  and  D,  near  to  D. 

Crystallized  methaemoglobin  may  be  easily  obtained  by  treating 
a  concentrated  solution  of  oxyhgemoglobin  with  a  sufficient  quanti- 
ty of  concentrated  potassium  ferricyanide  solution  to  give  the  mix- 
ture a  porter-brown  color.  After  cooling  to  0°  C.  add  \  vol.  cooled 
alcohol  and  allow  the  mixture  to  stand  a  few  days  in  the  cold.  The 
crystals  may  be  easily  purified  by  recrystallizing  from  water  by  the 
addition  of  alcohol. 

Carbon  monoxide  methaemoglobin  has  been  prepared  by  Weyl  and  v. 
Ansep  by  the  action  of  potassium  permanganate  on  carbon  monoxide  haemo- 
globin. Sulphur  methaemoglobin  is  the  same  given  by  Hoppe-Seyler  to  that 
coloring  matter  which  is  formed  by  the  action  of  sulphuretted  hydrogen  on 
oxyhiBmoglobin.  The  solution  has  a  greenish-red,  dirty  color  and  shows  an 
absorption-band  in  the  red.  This  coloring  matter  is  claimed  to  be  the  greenish 
color  seen  on  the  surface  of  putrefj'iug  flesh. 

Decomposition  products  of  the  Uood  coloring  matters.  By 
its  decomposition  haemoglobin  yields,  as  above  stated,  albumin  and 
a  ferruginous  coloring  matter  as  chief  products.  If  the  de- 
composition takes  place  in  the  absence  of  oxygen,  a  coloring  matter 


76  PHYSIOLOGICAL   CHEMISTRY. 

is  obtained  which  is  called  by  Hoppe-Setler  hmmochromogen,  by 
other  investigators  (Stokes)  reduced  hmnatin.  In  the  presence 
of  oxygen,  hsemochromogen  is  quickly  oxidized  to  haematin,  and 
we  obtain  in  this  case  as  a  colored  decomposition  product 
another  coloring  matter,  limmatin.  As  hgemochromogen  is  easily 
converted  by  oxygen  into  haematin,  so  this  latter  may  be  reconverted 
into  hgemochromogen  by  reducing  substances. 

Hsemochromogen  was  discovered  by  Hoppe-Setler  to  whom  of 
all  investigators  we  are  more  indebted  for  our  knowledge  in  regard 
to  the  blood-coloring  matters  and  their  decomposition  products.  He 
has  also  lately  been  able  to  obtain  this  coloring  matter  as  crystals. 
Haeniochromogen  is,  according  to  Hoppe-Seyler,  the  colored 
atomic  group  of  haemoglobin  and  its  combination  with  gases, 
and  this  atomic  group  is  combined  with  albumin  in  the  coloring 
matter.  The  characteristic  absorption  of  •  light  depends  on  the 
hsemochromogen,  and  it  is  also  this  atomic  group  which  binds  in 
the  oxyhaemoglobin  1  mol.  oxygen  and  in  the  carbon  monoxide 
haemoglobin  1  mol.  carbon  monoxide  with  1  atom  iron.  Hoppe- 
Setler  has  observed  a  combination  between  haemochromogen  and 
carbon  monoxide,  and  this  combination  shows  the  spectral  appear- 
ance of  carbon  monoxide  hsemoglobin. 

An  alkaline  haemochromogen  solution  has  a  beautiful  red  color. 
It  shows  two  absorption-bands,  first  described  by  Stokes,  of  which 
the  one  is  darker  and  lies  between  B  and  E,  and  the  other,  broader 
but  not  so  dark,  covers  the  lines  E  and  h.  In  acid  solution  haemo- 
chromogen shows  four  bands,  which  according  to  Jaderholm  de- 
pend on  a  mixture  of  hgemochromogen  and  haematoporphyrin  (see 
below),  this  last  formed  by  a  partial  decomposition  resulting  from  the 
action  of  the  acid. 

Haemochromogen  may  be  obtained  as  crystals  by  the  action  of 
caustic  soda  on  hsemoglobin  at  100°  C.  in  the  absence  of  oxygen 
(Hoppe-Setler).  By  the  decomposition  of  hsemoglobin  by  acids 
(of  course  in  the  absence  of  air)  we  obtain  haemochromogen  con- 
taminated with  a  little  haematoporphyrin.  An  alkaline  haemochro- 
mogen solution  is  easily  obtained  by  the  action  of  a  reducing  sub- 
stance (Stokes'  reduction  liquid)  in  an  alkaline  haematin  solution. 

Haematin,  also  called  Oxyhsematin,  is  sometimes  found  in  old 
transudations.     It  is  formed  by  the  action  of  gastric  or  pancreatic 


THE  BLOOD.  77 

juices  on  oxyhasmoglobin,  and  is  therefore  also  found  in  the  faeces 
after  hemorrhage  in  the  intestinal  canal,  and  also  after  a  meat  diet 
and  food  rich  in  blood.  It  is  stated  that  hsematin  may  occur 
in  urine  after  poisoning  with  arseniuretted  hydrogen.  As  sliown 
above,  the  haematin  is  formed  by  the  decomposition  of  oxyhemo- 
globin, or  at  least  of  haemoglobin,  in  the  presence  of  oxygen. 

The  constitution  of  hsematin  may,  according  to  Hoppe-Setler, 
be  expressed  by  the  formula  Ca^HssNiFeOs.  According  to  Nencki 
and  SiEBER  it  has  the  formula  CsaH^^NiFeOi ,  and  they  claim  that 
hgematin  consists  of  a  body  not  yet  isolated,  hgemin,  CagHsoN^FeOa  > 
with  1  mol.  H.O. 

Haematin  is  amorphous,  dark  brown  or  bluish  black.  It  may 
be  heated  to  180°  C.  without  decomposition;  on  burning  it  leaves  a 
residue  consisting  of  iron  oxide.  It  is  insoluble  in  water,  dilute 
acids,  alcohol,  ether,  and  chloroform,  but  it  dissolves  slightly  in 
warm  glacial  acetic  acid.  Haematin  dissolves  in  acidified  alcohol 
or  ether.  It  easily  dissolves  in  alkalies,  even  when  very  dilute.  The 
alkaline  solutions  are  dichroitic;  in  thick  layers  they  appear  red  by 
reflected  light,  and  in  thin  layers  greenish.  The  alkaline  solutions 
are  precipitated  by  lime-  and  baryta-water,  as  also  by  solutions  of 
neutral  salts  of  the  alkaline  earths.  The  acid  solutions  are  always 
brown. 

An  acid  haematin  solution  absorbs  the  red  part  of  the  spectrum 
less  and  the  violet  part  more.  The  solution  shows  a  rather  sharply- 
defined  baud  between  C  and  D  whose  position  may  change  with  the 
variety  of  acid  used  as  a  solvent.  Between  D  and  F  a  second,  much 
broader,  less  sharply-defined  band  occurs  which  by  proper  dilution 
of  the  liquid  is  converted  into  two  bands.  The  one  between  i  and  F, 
lying  near  F,  is  darker  and  broader,  the  other,  between  D  and  E, 
lying  near  E,  is  lighter  and  narrower.  Also  by  proper  dilution  a 
fourth  very  faint  band  is  observed  between  D  and  E  lying  near  D. 
Hsematin  may  thus  in  acid  solution  show  four  absorption-bands; 
ordinarily  one  sees  distinctly  only  the  bands  between  C  and  D 
and  the  broad,  dark  band — or  'the  two  bands — between  D  and  F. 
In  alkaline  solution  the  haematin  shows  a  broad  absorption-band, 
which  lies  in  greatest  part  between  C  and  D,  but  reaches  a  little 
over  the  line  D  towards  the  right  in  the  space  between  D  and  E. 

Haematin  is  dissolved  by  concentrated   sulphuric   acid  in  the 


78  PHYSIOLOGICAL  CHEMISTRY. 

presence  of  air,  forming  a  purple-red  liquid.  The  iron  is  here 
split  off  and  the  new  coloring  matter,  called  hmmatoporphyi-in  by 
Hoppe-Setlee,  is  iron-free.  The  hsematin  yields  with  concentrat- 
ed sulphuric  acid,  in  the  absence  of  air,  a  second  iron-free  coloring 
matter  called  hcematolin  (Hoppe-Seylee).  Hsematoporphyrin  may 
also  be  prepared  by  the  action  of  glacial  acetic  acid  saturated  with 
hydrobromic  acid  on  hsemin  crystals  (Nekcki  and  Siebee).  This 
coloring  matter  is,  according  to  Nei^cki  and  Siebee,  an  isomer 
of  the  bile-coloring  matter  bilirubin,  and  the  formula  is,  according 
to  them,  CigHisNgOs.  The  formation  of  haematoporphyrin  from 
haematin  occurs  according  to  the  following  equation : 

CaAgNiOiFe  +  2H2O  -  Fe  =  2(Ci6Hi8N203). 

The  combinations  of  haematoporphyrin  with  Na  and  with  HCl 
have  been  obtained  as  crystals  by  Nencki  and  Siebee.  The 
haematoporphyrin  prepared  by  them  does  not  seem  to  be  identical 
with  that  prepared  by  Hoppe-Seylee  even  though  they  have  the 
same  spectrum.  A  dilute  solution  with  alkali  carbonate  shows  a 
spectrum  with  four  absorption-bands,  namely,  a  band  between  C 
and  D;  a  second,  broader,  surrounding  D  and  with  its  broadest 
part  between  D  and  E;  a  third,  lighter  and  narrower,  between  D 
and  E;  and  lastly  a  fourth,  broad  and  dark  band  between  h  and  F. 
By  the  action  of  reducing  agents  on  hgematoporphyrin  a  coloring 
matter  has  been  obtained  which  stands  closely  related  to  urobi- 
lin (Hoppe-Seylee,  Neistcki  and  Siebee).  Haematoporphyrin 
occurs  also  in  the-  animal  kingdom  preformed  (MacMuni^). 

Hsemin,  H^min"  Ceystals,  or  Teichmann's  Ceystals.  Hae- 
min,  according  to  Hoppe-Seylee,  is  a  combination  between  hae- 
matin and  hydrochloric  acid, having  the  formula  Cs^HgsNiFeOs.HCl. 
Nencki  and  Siebee  designate  as  haemin,  on  the  contrary  (see  page 
77),  a  body  not  yet  isolated,  of  the  formula  CssHsoNiFeOg ,  which 
may  be  considered  as  haematin  —  HgO  or  OagHsglSriFeOi  —  HjO. 
The  haemin  crystals  are,  according,  to  the  latest  views,  a  combina- 
tion of  this  substance,  haemin,  and  HCl,  according  to  the  formula 
C32H3oN,Fe03.HCl. 

According  to  the  same  experimenters,tbe  haemin  crystals  are  a  double  com- 
bination with  the  solvent,  amyl  alcohol  or  acetic  acid,  which  is  used  in  their 
preparation;  while  Hoppe-Seyler  claims  that  the  solvent  is  only  held  me- 


THE  BLOOD.  79 

chauically  by  the  crystals.     The  formula  of  the  haemin  crystals  prepared  by 
means  of  amyl  alcohol  is,  according  to  Nencki  and  Siebek, 

(C32H3oN4Fe03.HCl)4.C5Hi20. 

Haemin  crystals  form  in  large  masses  a  bluish-black  powder,  but 
are  so  small  individually  that  they  can  only  be  seen  by  the  micro- 
scope. They  consist  of  dark-brown  or  nearly  brownish-black,  long, 
rhombic,  or  spool-like  crystals,  isolated,  or  grouped  as  crosses, 
rosettes,  or  starry  forms.  They  are  insoluble  in  water,  dilute  acids 
at  the  normal  temperature,  alcohol,  ether,  and  chloroform.  They 
are  slightly  dissolved  by  glacial  acetic  acid  and  warmth.  They 
dissolve  in  acidified  alcohol,  as  also  in  dilute  caustic  or  carbonated 
alkalies;  and  in  the  last  case  they  form,  besides  alkali  chlorides, 
soluble  hasmatin  alkali,  from  which  the  haematin  may  be  precipi- 
tated by  an  acid. 

The  preparation  of  haemin  crystals  is  always  the  starting-point 
for  the  preparation  of  haematin.  According  to  Hoppe-Seyleb, 
shake  the  blood-corpuscles  which  have  been  washed  with  common- 
salt  solution  (see  page  66)  with  water  and  ether,  then  filter  the  solu- 
tion of  blood-coloring  matters,  concentrate  strongly,  mix  with  10-20 
vols,  glacial  acetic  acid,  and  heat  for  1-2  hours  on  the  water-bath. 
After  diluting  with  several  volumes  of  water,  allow  the  liquid  to 
stand  a  few  days.  The  crystals  which  separate  are  then  washed 
with  water,  boiled  with  acetic  acid,  and  then  washed  again  with 
water,  alcohol,  and  ether,  Nencki  and  Siebek  coagulate  the 
sediment  of  the  blood-corpuscles  by  alkali,  allow  the  coagulum  to 
dry  incompletely  in  the  air,  rub  it  fine,  and  then  boil  it  with  amyl 
alcohol  after  the  addition  of  a  little  hydrochloric  acid.  The  crys- 
tals which  separate  from  the  filtrate  after  cooling  are  washed  with 
water,  alcohol,  and  ether.  If  haemin  crystals  be  dissolved  in  dilute 
caustic  alkali,  hgematin  may  be  precipitated  from  the  solution  by 
the  addition  of  acid;  and  from  this  haematin  pure  haemin  crystals 
may  be  prepared  by  heating  with  glacial  acetic  acid  and  a  little 
common  salt. 

In  preparing  haemin  crystals  in  small  amounts  proceed  in  the 
following  manner:  The  blood  is  dried  after  the  addition  of  a  small 
quantity  of  common  salt,  or  the  dried  blood  may  be  rubbed  with  a 
trace  of  common  salt.  The  dry  powder  is  placed  on  a  microscope- 
slide,  moistened  with  glacial  acetic  acid,  and  then  covered  with  the 
cover-glass.  Add,  by  means  of  a  glass  rod,  more  glacial  acetic  acid 
by  applying  the  drop  at  the  edge  of  the  cover-glass,  until  the  space 
between  the  slide  and  the  cover-glass  is  full.  Now  warm  over  a  very 
small  flame,  with  the  precaution  that  the  acetic  acid  does  not  boil 


80  PHYSIOLOGICAL   CHEMISTRY. 

and  pass  with  the  powder  from  under  the  cover-glass.  If  no  crys- 
tals appear  after  the  first  warming  and  cooling,  warm  again,  and  if 
necessary  add  some  more  acetic  acid.  After  cooling,  if  the  experi- 
ment has  been  properly  performed,  a  number  of  dark-brown  or 
nearly  black  haemin  crystals  of  varying  forms  will  be  seen. 

Haematoidin,  thus  called  by  Viechow^,  is  a  coloring  matter 
which  crystallizes  in  orange-colored  rhombic  plates,  and  which 
occurs  in  old  blood  extravasations,  and  whose  origin  from  the 
blood-coloring  matters  seems  to  be  established  (Langhans, 
CoRDUA,  Quincke,  and  others).  A  solution  of  haematoidin  shows 
no  absorption-bands,  but  only  a  strong  absorption  of  the  violet 
to  the  green  (Ewald).  According  to  most  observers,  haema- 
toidin is  identical  with  the  bile-coloring  matter  bilirubin.  It  is 
not  identical  with  the  crystallizable  lutein  from  the  corpora  lutea 
of  the  ovaries  of  the  cow  (Piccolo  and  Liebetst,  Kithne  and 
Ewald). 

In  the  detection  of  the  above-described  blood-coloring  matters 
the  spectroscope  is  the  only  entirely  trustworthy  means  of  investi- 
gation. If  it  is  only  necessary  to  detect  blood  in  general  and  not 
to  determine  definitely  whether  the  coloring  matter  is  haemoglobin, 
methasmoglobin,  or  haematin,  then  the  presence  of  haemin  crystals 
is  an  absolute  positive  proof.  The  reader  is  referred  to  more 
extended  text-books  for  exacter  methods  for  the  detection  of  blood 
in  chemico -legal  cases,  and  it  is  perhaps  sufficient  to  give  here  the 
chief  points  of  the  investigation. 

If  spots  on  clothes,  linen,  wood,  etc.,  are  to  be  tested  for  the  pres- 
ence of  blood,  it  is  best,  when  possible,  to  scratch  or  shave  off  as 
much  as  possible,  rub  with  common  salt,  and  from  this  prepare  the 
haemin  crystals.  On  obtaining  positive  results  the  presence  of 
blood  is  not  to  be  doubted.  If  you  do  not  obtain  sufficient  material 
by  the  above  means,  then  soak  the  spot  with  a  few  drops  of  water 
in  a  watch-crystal.  If  a  colored  solution  is  thus  obtained,  then 
remove  the  fibres,  wood-shavings,  and  the  like  as  far  as  possible, 
and  dry  all  the  solution  in  a  watch-glass.  The  dried  residue  may 
be  partly  used  for  the  spectroscope  test  directly,  and  part  may  be 
employed  in  the  preparation  of  the  haemin  crystals.  It  also  serves 
to  detect  haemochromogen  in  alkaline  solution  after  previous  treat- 
ment with  alkali  and  the  addition  of  reducing  substances. 

If  a  colorless  solution  is  obtained  after  soaking  with  water,  or 
the  spots  are  on  rusty  iron,  then  digest  with  a  little  dilute  alkali 
(5  p.  m.).  In  the  presence  of  blood  the  solution  gives,  after  neu- 
tralization with  hydrochloric  acid  and  drying,  a  residue  which  may 


THE  BLOOD.  81 

give  the  haemin  crystals  with  glacial  acetic  acid.  Another  part  of 
the  alkaline  solution  shows,  after  the  addition  of  Store's  reduc- 
tion liquid,  the  absorption-bands  of  haemochromogen  in  alkaline 
solution. 

The  methods  proposed  for  the  quantitative  estimation  of  the 
blood-coloring  matters  are  partly  chemical  and  partly  physical. 

Among  the  chemical  methods  to  be  mentioned  is  the  ashing  of  the  blood 
and  the  determination  of  the  amount  of  iron  contained  therein,  from  which 
the  amount  of  haemoglobin  may  be  calculated.  Another  method  consists  in 
first  saturating  the  blood  completely  with  oxygen.  Now  pump  out  thor- 
oughly this  oxygen,  and  calculate  from  the  amount  of  oxygen  the  amount  of 
haemoglobin  present  (Grehant  and  Quinquatjd).  None  of  these  methods  is 
reliable. 

The  physical  methods  consist  either  in  a  colorimetric  or  a  spec- 
troscopic investigation. 

The  principle  of  Hoppe-Seyler's  colorimetric  method  is  that  a 
measured  quantity  of  blood  is  diluted  with  an  exactly  measured 
quantity  of  water  until  the  diluted  blood  solution  has  the  same 
color  as  a  pure  oxyhgemoglobin  solution  of  a  known  strength.  The 
amount  of  coloring  matter  present  in  the  undiluted  blood  may  be 
easily  calculated  from  the  degree  of  dilution.  In  the  colorimetric 
testing  we  use  a  glass  vessel  with  parallel  sides  containing  a  layer 
of  liquid  1  cm.  thick  (haematinometer  of  Hoppe-Setler).  The 
method  is  good,  and  the  inconvenience  that  the  normal  solution 
of  oxyhaemoglobin  does  not  keep  for  any  length  of  time  without  de- 
composing may  be  prevented  by  preserving  the  solution  in  sealed 
tubes.  The  oxyhaemoglobin  is  gradually  reduced  to  a  hsemoglobin 
solution  which  may  be  kept  for  years,  and  when  required  for  use  it 
is  converted  into  an  oxyhaemoglobin  solution  by  aerating.  A  few 
observers  (Eajewskt,  Lesser,  Mallassez)  have  tried  to  replace 
the  oxyhemoglobin  solution  by  a  solution  of  picrocarmin. 

The  quantitative  estimation  of  the  blood-coloring  matters  by 
means  of  the  spectroscope  may  be  done  in  different  ways,  but  at 
the  present  time  the  spectropliotometric  method  is  chiefly  used,  and 
this  seems  to  be  the  most  reliable.  This  method  is  based  on  the 
fact  that  the  extinction  coefficient  of  a  colored  liquid  for  a  certain 
region  of  the  spectrum  is  directly  proportional  to  the  concentra- 
tion, so  that  C  :  E  =  C^  :  ^, ,  when  C  and  C,  represent  the  differ- 
ent concentrations  and  B  and  E  the  corresponding  coefficient  of 

C      C 
extinction.     From  the  equation  —  =  — i  it  follows  that  for  one  and 

E       E^ 

the  same  coloring  matter  this  relation,  which  is  called  the  absorp- 
tion ratio,  must  be  constant.  If  the  absorption  ratio  is  represented 
by  A,  the  determined  extinction  coefficient  by  E,  and  the  concen- 


82  PHYSIOLOGICAL   CHEMISTRY. 

tration  (the  amount  of  coloring  matter  in  grams  in  1  c.  c.)  by  C, 
then  C^  A.E. 

Different  apparatus  have  been  constructed  (Vierordt  and 
HtJfner)  for  the  determination  of  the  extinction  coefficient  which 
is  equal  to  the  negative  logarithm  of  those  rays  of  light  which 
remain  after  the  passage  of  the  light  through  a  layer  1  cm.  thick 
of  an  absorbing  liquid.  In  regard  to  these  apparatus  the  reader  is 
referred  to  other  text-books. 

As  control  the  exliuction  coeflBcients  are  determined  in  two  different 
regions  of  the  spectrum,  namely,  i>32^—Z)54E?  and  DmE—BSiE.  The 
constants  or  the  absorption  ratio  for  these  two  regions  of  the  spectrum  are 
designated  by  Hefner  by  A  and  A'.  Before  the  determination  the  blood 
must  be  diluted  with  water,  and  if  the  proportion  of  dilution  of  the  blood  be 
represented  by  V,  then  the  concentration  or  the  amount  of  coloring  matter  in 
100  parts  of  the  undiluted  blood  is 

C  =  100  .  V  .  A  .  E    and 
C'=100.  r.A'.  E'. 

The  absorption  ratio  or  the  constants  in  the  two  above-mentioned  regions 
of  the  spectrum  have  been  determined  for  oxyhaemoglobin,  haemoglobin, 
carbon  monoxide  haemoglobin,  and  methaemoglobiu. 

The  figures  for  the  above  coloring  matters  obtained  from  canine  blood  are 
as  follows : 

Oxyhaemoglobin Ao  =  0.001330  and  Ao  =  0.001000 

Haemoglobin Ar  =  0.001091    "    Ar  -  0.001351 

Carbon  monoxide  haemoglobin  A  =  0.001130    "    Ac  =  0.001000 
Methaemoglobin Am—  0.003696    "    J.m'=  0.002798 

The  quantity  of  each  coloring  matter  may  be  determined  in  a  mixture  of 
two  blood-coloring  matters  by  this  method,  which  is  of  special  importance  in 
the  determination  of  the  quantity  of  oxyhaemoglobin  and  haemoglobin  present 
in  blood  at  the  same  time.  If  we  represent  by  ^and  E'  the  extinction  co- 
eflBcients of  the  mixture  in  the  above-mentioned  regions  of  the  spectrum,  by 
Ao  and  Ao  and  Ar  and  Ar  the  constants  for  oxyhaemoglobin  and  reduced 
haemoglobin,  and  by  Fthe  degree  of  dilution  of  the  blood,  then  the  percentage 
of  oxyhaemoglobin  Ho  and  of  (reduced)  haemoglobin  Hr  is 

TT       ^(^(^     V    ^o^oJEAr  -  E'Ar') 

Mo  —   iUU  .     V  .    .    ,   . ;; — -7—, 

Ao  Ar  —  AoAr 

and 

H  =100     V   -^rAr'jEAo'-  EAo) 

Among  the  many  apparatus  constructed  for  clinical  purposes 
for  the  quantitative  estimation  of  hagmoglobin  the  haemometer  of 
Fleischl  is  to  be  preferred.  The  determination  by  this  apparatus 
is  made  by  comparing  the  color  of  the  blood  diluted  with  water 
with  the  color  of  a  wedge-shaped  movable  prism  of  red  glass.  If 
the  blood  shows  the  same  color  as  the  glass  prism,  then  the  amount 
of  haemoglobin  in  the  blood  may  be  directly  read  from  the  scale. 


THE  BLOOD.  83 

The  amount   of   hasmoglobin   is   expressed  as  percentage  of  the 
physiological  amount  of  haemoglobin. 

Many  other  coloring  matters  are  found  besides  the  often-occurring  haemo- 
globin in  the  blood  of  invertebra.  In  a  few  arachnidae,  Crustacea,  gasteropodse, 
and  cephalopodae  a  body  analogous  to  haemoglobin  containing  copper,  hmmo- 
cyanin,  has  been  found.  B}'^  the  taking  up  of  loosely-bound  oxygeu  this  body 
is  converted  into  blue  oxyhmnocyanin  (P.  Bert,  Fkedericq,  Krukenberg, 
MacMunn),  and  by  the  escape  of  the  oxygen  becomes  colorless  again.  A 
coloring  matter  called  chlorocruorin  by  Lankester  is  found  in  certain 
chaetopodse.  Hcemerythrin,  so  called  by  Krukenberg  but  first  observed  by 
ScHWAL,BE,  is  a  red  coloring  matter  from  a  few  gephyrea.  Besides  haemo- 
cyauin  we  fiud  in  the  blood  of  certain  Crustacea  the  red  coloring  matter 
tetronerythriti  (Halliburton),  which  is  also  widely  spread  in  the  animal 
kingdom.  Echinochrom,  so  named  by  MacMunn,  is  a  brown  coloring  matter 
occurring  in  the  perivisceral  tluid  of  a  variety  of  echinoderms. 

The  quantitative  constitution  of  the  red  hlood-corpusdes  is 
difficult  to  determine  and  we  have  hardly  any  sufficiently  trust- 
worthy analyses  of  them.  The  amount  of  water  varies  in  different 
varieties  of  blood  between  570-630  p.  m.,  with  a  proportional 
amount,  430-370  p.  m.,  of  solids.  In  the  blood  of  mammalia  the 
chief  mass  (about  nine  tenths)  of  the  dried  substance  consists  of 
haemoglobin. 

According  to  the  analyses  of  Hoppe-Seyler  and  his  pupils,  the 
red  corpuscles  contain  in  1000  parts  of  the  dried  substance: 


Hasmoglobin. 

Albumin. 

Lecithin. 

Cholesterin, 

Human  blood . . 

..    868-943 

122-51 

7.2-3.5 

2.5 

Dog           •  ■     . . 

..       865 

126 

6.0 

4.0 

Goose         "     . . 

..       627 

364 

5.0 

5.0 

Snake        "     . . 

..       467 

525 

• .  • 

Of  special  interest  is  the  varying  proportion  of  the  hasmo- 
globin  to  the  albumin  in  the  nucleated  and  in  the  non-nucleated 
blood-corpuscles.  These  last  are  much  richer  in  hsemoglobin  and 
poorer  in  albumin  than  the  others.  The  amount  of  mineral  bodies, 
as  far  as  they  have  been  determined,  in  the  moist  corpuscles  is  4.8- 
8.9  p.  m.  The  chief  mass  consists  of  potassium,  phosphoric  acid, 
and  chlorine.  The  blood-corpuscles  of  ox-blood  contain,  accord- 
ing to  BuNGE,  more  sodium  and  chlorine  than  phosphoric  acid  and 
potassium.  The  blood-corpuscles  of  the  pig  and  horse  contain  no 
sodium  (Bunge).  Human-blood  corpuscles  contain,  according  to 
Wanach,  about  five  times  as  much  potassium  as  sodium,  on  an 
average  3.99  p.  m.  potassium  and  0.75  p.  m.  sodium. 


84  PHTSIOLOOIGAL   CHEMISTRY. 

The  Colorless  Blood-corpuscles  and  the  Blood-tahlets. 

The  Colorless  Blood  -  corpuscles,  also  called  Leucocytes  or 
Lymphoid  Cells,  which  occur  in  the  blood  in  varying  forms  and 
sizes,  form  in  a  state  of  rest  spherical  lumps  of  a  sticky,  highly 
refractive  power,  capable  of  motion,  non-membranous  protoplasm, 
which  show  1-4  nuclei  on  the  addition  of  water  or  acetic  acid.  In 
human  and  mammalial  blood  they  are  larger  than  the  red  blood- 
corpuscles.  They  have  also  a  lower  specific  gravity  than  the  red 
corpuscles,  move  in  the  circulating  blood  nearer  to  the  walls  of  the' 
vessel,  and  have  also  a  slower  motion. 

The  number  of  colorless  blood-corpuscles  varies  not  only  in  the 
different  blood-vessels,  but  also  under  different  physiological  con- 
ditions. As  an  average  we  have  only  1  colorless  corpuscle  for  350- 
500  red  corpuscles.  According  to  the  investigations  of  Alex. 
Schmidt  and  his  pupils,  the  leucocytes  are  destroyed  in  great  part 
— about  11<fo  in  the  blood  of  the  horse,  according  to  Hetl — on  the 
discharge  of  the  blood  before  and  during  coagulation,  so  that  dis- 
charged blood  is  much  poorer  in  leucocytes  than  the  circulating 
blood.  The  correctness  of  this  statement  has  been  denied  by  other 
investigators. 

From  a  histological  standpoint  we  generally  distinguish  the 
different  kinds  of  colorless  blood-corpuscles;  chemically  considered, 
however,  there  is  no  known  essential  difference  between  them. 
With  regard  to  their  importance  in  the  coagulation  of  fibrin 
Alex.  Schmidt  and  his  pupils  distinguish  between  the  leucocytes 
which  are  destroyed  by  the  coagulation  and  those  which  are  not. 
The  last  mentioned  are  colored  quickly  by  carmine  and  give  with 
alkalies  or  common-salt  solutions  a  slimy  mass;  the  first  do  not 
show  such  behavior. 

The  protoplasm  of  the  leucocytes  has  during  life  amoeboid 
movements  which  partly  make  possible  the  wandering  of  the  cells 
and  partly  the  taking  up  of  smaller  grains  or  foreign  bodies 
within  the  same.  On  these  grounds  the  occurrence  of  myosin  in 
them  has  been  admitted  even  without  any  special  proof  thereof. 
Alex.  Schmidt  found  semm  glohtiUn  in  equine-blood  leucocytes 
which  had  been  washed  with  ice-cold  water.  There  are  also 
at  least  certain  leucocytes  which  yield  a  slimy  mass  when  treated 


THE  BLOOD.  85 

with  alkalies  or  NaCl  solutions,  which  seem  to  be  identical  with 
the  so-called  hyaline  substance  of  Kovida  found  in  the  pus-cells. 
On  digesting  the  leucocytes  with  water  a  solution  of  a  proteid  body- 
is  obtained  which  can  be  precipitated  by  acetic  acid  and  which  is 
not  soluble  in  an  excess  of  the  acid  (Schmidt  and  Rauschen- 
BACH,  Wooldridge).  This  proteid  substance,  designated  "  lyniph- 
fibrinogen  "  by  Wooldridge,  when  obtained  from  certain  leucocytes 
(but  not  from  others)  has  a  powerful  action  on  the  coagulation  of 
fibrin.  An  important  constituent  of  the  colorless  corpuscles  is, 
according  to  Alex.  Schmidt,  the  fibrin  ferment  or  perhaps  more 
correctly  a  mother-substance  of  the  same,  a  zymogen.  In  the 
destruction  of  the  colorless  corpuscles  the  fibrin  ferment  is  set  free 
and  serum  globulin  also  passes  into  the  plasma  at  the  same  time. 
Halliburton  has  isolated  two  globulins  and  one  albumin  (see 
page  43)  from  the  leucocytes  of  the  lymphatic  glands,  besides  Rovi- 
da's  hyaline  substance,  and  albumoses  and  peptones  as  post-mortem 
products. 

Among  the  other  constituents  of  the  pale  corpuscles  we 
must  mention  glycogen,  which  occurs  in  the  living  but  not  in  the 
dead  cell,  lecithin,  protagon  (?),  and  cliolesterin.  The  nucleus 
consists  without  doubt  of  nuclein.  The  mineral  constituents  are 
probably  the  same  as  in  the  pus-cells  (see  Chapter  V). 

The  above  statements  in  regard  to  the  constituents  of  the  leuco- 
cytes cover  not  only  the  pale  blood-corpuscles,  but  also  the  leuco- 
cytes of  the  lymphatic  glands.  The  leucocytes  of  the  blood  are 
considered  as  cells  pierced  from  the  outside,  and  it  is  probably  the 
correct  view  because  we  know  of  no  specific  chemical  properties 
or  constituents  in  the  leucocytes  of  the  blood  which  differ  from 
those  of  other  leucocytes. 

The  blood-tablets  (Bizzozero's),  whose  nature  and  physiological 
importance  have  been  much  questioned,  are  pale,  colorless,  gummy 
disks,  round  or  more  oval  in  shape  and  generally  with  a  diameter 
two  or  three  times  smaller  than  the  red  blood-corpuscles.  Their 
number,  according  to  Fusari,  in  healthy  persons  is  180,000-250,000 
in  1  c.mm.  Certain  investigators,  for  example  Bizzozero, 
ScHiMMELBUSCH,  and  Laker,  claim  that  the  blood-tablets  occur 
preformed  in  the  circulating  blood,  while  others,  for  instance 
LowiT  and  Wooldridge,  deny  this.     Other  investigators  (Hlaya) 


86  PHTSIOLOOICAL   CHEMISTRY. 

claim  that  they  may,  at  least  in  part,  be  formed  from  the  colorless 
blood-corpuscles,  while  Lowit  claims  that  they  are  formed  by  the 
withdrawal  of  globulin  substance  from  the  white  blood-corpuscles. 
BizzozEKO  and  several  other  investigators  consider  the  blood-tablets 
as  the  starting-point  for  the  coagulation  of  the  blood,  while  Alex. 
Schmidt's  pupils  deny  this.  Lowit  claims  that  the  blood-tablets 
are  formed  from  globulin  substance,  and  has  therefore  given  them 
the  name  globulin  tablets.  The  relationship  of  these  blood-tablets 
to  the  fibrin  coagulation  will  be  spoken  of  shortly. 

III.  The  Blood  as  a  Mixture  of  Plasma  and  Blooa- 
corpuscles. 

The  blood  in  itself  is  a  thick,  sticky,  lighter  or  darker  red  opaque 
liquid  having  a  salty  taste  and  even  in  thin  layers  a  faint  odor  dif- 
fering in  different  kinds  of  animals.  On  the  addition  of  sulphuric 
acid  to  the  blood  the  odor  is  more  pronounced.  In  adult  human 
beings  the  specific  gravity  averages  1.055,  ranging  between  1.045 
and  1.075.  According  to  Soheerej^ziss  the  foetal  blood  has  a  lower 
specific  gravity  than  the  blood  of  grown  persons.  Lloyd  E.  Jones 
found  that  the  specific  gravity  is  highest  at  birth  and  lowest  in 
children  when  about  two  years  old  and  in  pregnant  women. 

The  reaction  of  the  blood  is  alkaline.  The  amount  of  alkali, 
calculated  as  Na2C03,  is  in  the  dog  about  2  (Zuk'tz),  in  rabbits 
about  2.5  (Lassar),  and  in  man  3.38-3.90  p.  m.  (v.  Jaksch). 
The  alkaline  reaction  diminishes  outside  of  the  body,  and  indeed 
the  more  quickly  the  greater  the  original  alkalinity  of  the  blood. 
This  depends  on  the  formation  of  acid  in  the  blood,  in  which  the 
red  blood-corpuscles  seem  to  take  part  in  some  way  or  another. 
After  excessive  muscular  activity  the  alkalinity  is  diminished  on 
account  of  the  formation  of  acid  in  the  muscles,  and  it  is  also 
decreased  after  the  continuous  use  of  acids  (Lassar). 

The  color  of  the  blood  is  red — light  scarlet-red  in  the  arteries  and 
dark  bluish-red  in  the  veins.  Blood  free  from  oxygen  is  dichroitic, 
dark  red  by  reflected  light,  and  green  by  transmitted  light.  The 
blood-coloring  matters  occur  in  the  blood-corpuscles.  For  this 
reason  blood  is  opaque  in  thin  layers  and  acts  as  a  "deckfarbe." 
If  the  haemoglobin  is  removed  from  the  stroma  or  dissolved  from 


THE  BLOOD.  87 

the  blood-liquid  by  any  of  the  above-mentioned  means  (see  page  66) 
the  blood  becomes  transparent  and  acts  then  like  a  "lacfarbe." 
Less  light  is  now  reflected  from  its  interior,  and  this  latter  blood 
is  therefore  darker  in  thicker  layers.  On  the  addition  of  salt 
solutions  to  the  blood-corpuscles  they  shrink  and  more  light  is 
reflected  and  the  color  appears  lighter.  A  great  abundance  of  red 
corpuscles  makes  the  blood  darker,  while  by  diluting  with  serum  or 
by  a  greater  abundance  of  white  corpuscles  the  blood  becomes 
lighter  in  appearance.  The  different  colors  of  arterial  and  of  ven- 
ous blood  depend  on  the  varying  quantity  of  gas  contained  in  these 
two  varieties  of  blood,  or  better  on  the  different  amounts  of  oxy- 
haemoglobin  and  hsemoglobin  they  contain.  The  reason  for  the 
different  colors  of  these  two  varieties  of  blood  has  been  attributed 
in  part  to  the  unequal  forms  of  the  blood-corpuscles.  In  the  arterial 
blood  the  blood-corpuscles  are  considered  as  more  biconcave  and 
therefore  reflect  the  light  more  than  in  the  venous  blood  (Harless). 
These  statements  do  not  coincide  with  later  investigations. 

The  most  striking  property  of  blood  consists  in  its  coagulating 
within  a  shorter  or  longer  time,  but  as  a  rule  very  shortly  after 
leaving  the  vein.  Different  kinds  of  blood  coagulate  with  vary- 
ing rapidity;  in  human  blood  the  first  marked  sign  of  coagulation 
is  seen  in  2-3  minutes,  and  within  7-8  minutes  the  blood  is  thor- 
oughly converted  into  a  gelatinous  mass.  If  the  blood  is  allowed 
to  coagulate  slowly,  the  red  corpuscles  have  time  to  settle  more  or 
less  before  the  coagulation,  and  the  blood-clot  then  shows  an  upper, 
large,  yellowish-gi*ay  or  reddish -gray  layer  consisting  of  fibrin  en- 
closing chiefly  colorless  corpuscles.  This  layer  has  been  called 
crusta  inflammatoria  or  pJilogistica,  because  it  has  been  especially 
observed  in  inflammatory  processes,  and  is  considered  one  of  the 
characteristics  of  them.  This  crusta  or  "  huffy  coat "  is  not  char- 
acteristic of  any  special  disease,  and  it  occurs  chiefly  when  the  blood 
coagulates  slowly  or  when  the  blood-corpuscles  settle  more  quickly 
than  usual.  A  huffy  coat  has  been  observed  often  in  the  slow 
coagulation  of  equine  blood.  The  blood  from  the  capillaries  is  not 
supposed  to  have  the  power  of  coagulating. 

Coagulation  is  retarded  by  cooling,  by  diminishing  the  oxygen 
and  increasing  the  amount  of  carbon  dioxide,  which  is  the  reason 
that  venous  blood  and  to  a  much  higher  degree  blood  after  asphyx- 


88  PHYSIOLOGICAL   CEEMISTRT. 

iation  coagulates  more  slowly  than  arterial  blood.  The  coagulation 
may  be  retarded  or  prevented  by  the  addition  of  acids,  alkalies,  or 
ammonia,  even  in  small  quantities  ;  by  concentrated  solutions  of 
neutral  salts  or  alkalies  and  alkaline  earths ;  also  by  egg-albumin, 
solutions  of  sugar  or  gum,  glycerin,  or  much  water;  also  by  receiv- 
ing the  blood  in  oil.  The  coagulation  may  be  prevented  by  the  in- 
jection of  an  albumose  solution  or  by  an  infusion  of  the  leech  into 
the  circulating  blood,  but  this  infusion  of  the  leech  acts  in  the 
same  way  on  blood  just  expelled.  The  coagulation  may  be  facil- 
itated by  raising  the  temperature;  by  contact  with  foreign  bodies, 
to  which  the  blood  adheres  ;  by  stirring  or  beating  it ;  by  admission 
of  air;  by  diluting  with  very  small  amounts  of  water;  by  the  ad- 
dition of  platinum-black  or  finely-powdered  carbon;  by  the  addition 
of  lac-colored  blood,  which  does  not  act  by  the  presence  of  dissolved 
blood-coloring  matters,  but  by  the  stromata  of  the  blood-corpuscles 
(WooLDRiDGE,  Nuok),  and  also  by  the  addition  of  the  leucocytes 
from  the  lymphatic  glands,  or  a  watery  saline  extract  of  the  lymph- 
atic glands,  testicles,  or  thymus.  The  active  constituent  of  such  a 
watery  extract  is,  according  to  Wooldeidge,  an  albuminous  body 
containing  lecithin,  which  he  calls  tissue  fibrinogen. 

An  important  question  to  answer  is  why  the  blood  remains 
fluid  in  the  circulation  while  it  quickly  coagulates  when  it  leaves 
the  circulation. 

When  the  blood  leaves  the  vein  it  comes  under  new,  abnormal 
conditions.  It  cools  off,  it  comes  in  contact  with  the  air,  its 
motion  stops,  and  it  is  deprived  of  the  influence  of  the  living 
walls  of  the  vessels.  That  the  cooling  is  not  the  reason  of  the 
coagulation  is  proved  by  the  fact  that  cooling  is  a  good  means  of 
retarding  coagulation.  That  the  contact  with  air  is  not  essential 
is  shown  by  the  fact  that  when  blood  is  collected  over  mercury,  so 
that  it  cannot  absorb  or  expel  any  gas,  it  likewise  coagulates. 
That  the  cessation  of  the  motion  does  not  cause  the  coagulation 
follows,  since  blood  collected  over  mercury  coagulates  whether  it  is 
shaken  or  not,  and  further  from  the  fact  that  motion,  such  as 
beating  the  blood,  facilitates  the  coagulation. 

The  reason  why  blood  coagulates  on  leaving  the  body  is  there- 
fore to  be  sought  for  in  the  influence  which  the  walls  of  the  living 


THE  BLOOD.  89 

and  entire  blood-vessels  exert  upon  it.  These  views  are  derived 
from  the  observations  of  many  investigators.  From  the  observa- 
tions of  Hewsox,  Lister,  and  Fredekicq  it  is  known  that  when 
a  vein  full  of  blood  is  tied  at  the  two  ends  and  removed  from  the 
body,  the  blood  may  remain  fluid  for  a  long  time.  Brtjcke  allowed 
the  heart  removed  from  a  tortoise  to  beat  at  0°C.,  and  found  that 
the  blood  remained  uncoagulated  for  some  days.  The  blood  from 
another  heart  quickly  coagulated  when  collected  over  mercury.  In 
a  dead  heart,  as  also  in  a  dead  blood-vessel,  the  blood  soon  coagu- 
lates, and  also  when  the  walls  of  the  vessel  are  changed  by 
pathological  processes. 

What  then  is  the  influence  which  the  walls  of  the  vessels  exert  on 
the  liquidity  of  the  circulating  blood  ?  Freund  has  found  that 
the  blood  remains  fluid  when  collected  by  means  of  a  greased 
canula  under  oil  or  in  a  vessel  smeared  with  vaseline.  If  the  blood 
collected  in  a  greased  vessel  be  beaten  with  a  glass  rod  previously 
oiled,  it  does  not  coagulate,  but  it  quickly  coagulates  on  beating  it 
with  an  unoiled  glass  rod  or  when  it  is  poured  into  a  vessel  not 
greased.  The  non-coagulability  of  blood  collected  under  oil  has 
been  confirmed  later  by  Hatcraft  and  Carlier.  Freund  found 
•on  further  investigating  that  the  evaporation  of  the  upper  layers  of 
blood  or  their  contamination  with  small  quantities  of  dust  causes 
a  coagulation  even  in  a  vessel  treated  with  vaseline.  According 
to  Freund,  it  is  this  adhesion  between  the  blood  or  between  its 
form-elements  and  a  foreign  substance — and  the  diseased  walls 
of  the  vessels  also  act  as  such — that  gives  the  impulse  towards 
coagulation,  while  the  lack  of  adhesion  prevents  the  blood  from 
coagulating.  This  adhesion  of  the  form-elements  of  the  blood 
to  certain  foreign  substances  seems  to  induce  changes  which 
apparently  stand  in  a  certain  relationship  to  the  coagulation  of 
the  blood. 

That  view  of  the  coagulation  of  the  blood  which,  with  a  few 
modifications,  is  accepted  by  most  investigators  is  the  theory  pro- 
posed by  Alexander  Schmidt  and  the  Dorpat  School.  Accord- 
ing to  Alex.  Schmidt,  who  of  all  investigators  has  done  most  to 
elucidate  this  subject,  an  abundant  destruction  of  the  colorless  blood- 
corpuscles  takes  place  in  coagulation,  and  from  this  not  only  the 
fibrin  ferment  results,  but  also  serum  globulin  and  fibrinogen,  which 


90  PHYSIOLOGICAL  CHEMISTRY. 

last,  however,  was  previously  present  in  the  plasma.  Under  the 
action  of  the  fibrin  ferment  the  serum  globulin  and  fibrinogen  unite 
forming  fibrin.  In  the  coagulation  a  reciprocal  action  takes  place 
between  the  protoplasm  of  the  leucocytes  and  the  plasma,  so  that 
the  plasma  quickly  destroys  the  leucocytes  and  is  itself  destroyed  by 
the  setting  free  of  fibrin  •  ferment  with  the  separation  of  fibrin 
(Schmidt  and  Rauschenbach).  Such  an  exchange  action  not  only 
takes  place  between  the  blood-plasma  and  the  leucocytes,  but  also 
between  blood-plasma  and  animal  protoplasm  in  general — indeed, 
even  between  vegetable  protoplasm  and  blood-plasma  (Schmidt  and 
Geohmann).  While  the  blood-serum  in  general  acts  as  a  conser- 
vator on  the  cells,  the  blood-plasma  on  the  contrary  has  a  destruc- 
tive action,  and  this  action  develops  the  fibrin  ferment.  This  last- 
mentioned  is  chiefly  a  decomposition  product  of  the  cells  (Schmidt, 
EAUSCHEisrBACH ;  FoA  and  Pellacais^i),  and  it  may  therefore  be 
called  " protozym  "  (Rauschekbach).  A  destruction  of  the  leuco- 
cytes may  also  occur  in  the  blood  under  physiological  conditions,  and 
therefore  traces  of  fibrin  ferment  are  habitually  formed  in  the  blood. 
Within  certain  limits  the  organism  may  be  guarded  from  a  danger- 
ous increase  in  these  processes.  According  to  Schmidt  and  Gkoth, 
and  Schmidt  and  KEiJGER,the  injection  of  leucocytes  into  the  circu- 
lating blood  may  produce  an  intravascular  coagulation,  but  the  cor- 
rectness of  this  statement  is  denied  by  Wooldridge.  According 
to  him,  the  pure,  washed  leucocytes  are  inactive  and  the  action  ob- 
served by  Schmidt  and  his  pupils  is  caused  by  contamination  with 
"  lymphfihrinogen"  The  lymphfibrinogen  is  a  representative  of  an 
entire  group  of  protein  substances  which  are  precipitated  by  acetic 
acid,  contain  lecithin,  which  occur  in  many  organs  and  tissues  but 
which  have  not  been  closely  studied  and  which  Wooldridge  has 
named  "  tissue  fibrinogens." 

According  to  Alex.  Schmidt,  the  coagulation  of  the  blood  is  an 
enzymotic  process,  produced  by  the  fibrin  ferment,  in  which  two 
protein  substances,  the  serum  globulin  and  the  fibrinogen,  form  the 
material  substrata  of  the  fibrin.  There  is  no  basis  for  the  assump- 
tion that  the  serum  globulin  in  the  newly-formed  fibrin  exists 
otherwise  than  as  a  mechanical  contamination.  It  is  true  indeed 
that  the  strongly-contaminated  serum  globulin  prepared  from 
serum  containing  enzymes  accelerates  coagulation,  and  the  amount 


THE  BLOOD.  91 

of  separated  fibrin  under  the  circumstances  may  be  increased,  but 
pure  serum  globulin  prepared  from  transudation  free  from  enzymes 
is  inactive.  The  same  action  on  the  amount  of  fibrin  separated 
which  the  impure  serum  globulin  shows  also  occurs  by  the  action 
of  the  substance  precipitated  by  acetic  acid  from  a  watery  extract 
of  the  leucocytes  of  the  lymphatic  glands.  This  substance,  which 
is  neither  identical  with  serum  globulin  nor  contaminated  by  it, 
may,  according  to  Schmidt  and  Eauschexbach,  increase  the 
amount  of  fibrin  in  filtered  plasma  about  25^.  Finally,  a  fibrinogen 
solution  free  from  serum  globulin,  and  a  fibrin  ferment  solution 
also  free  from  serum  globulin,  may  yield  a  typical  fibrin  (Authoe). 
It  is  therefore  hardly  possible  to  accept  this  part  of  Schmidt's 
theory.  It  is  much  more  probable  that  the  impure  serum  globulin 
furthers  the  separation  of  the  fibrin  indirectly,  in  the  same  way  as 
CaClj  (Authoe)  and  the  lime  salts  in  general  (Geeen,  Keugee). 
It  is  a  fact  that  a  typical  fibrin  is  formed  from  fibrinogen  alone  in 
the  presence  of  fibrin  ferment  and  mineral  bodies  (alkali  chlorides 
and  lime  salts). 

In  regard  to  the  importance  of  the  colorless  blood-corpuscles  in 
the  coagulation  of  the  blood  opinions  are  somewhat  diverse.  Ac- 
cording to  Bizzozeeo  and  others,  it  is  not  the  colorless  blood- 
corpuscles  but  the  blood-tablets  which  represent  the  starting-point 
for  the  formation  of  fibrin,  a  view  against  which  weighty  objec- 
tions have  been  urged  by  Lowit  and  others.  Wooldeidge  also 
considers  the  colorless  blood-corpuscles  as  only  of  secondary  im- 
portance. As  found  by  him,  a  peptone-plasma  which  has  been 
freed  from  all  form-constituents  by  centrifugal  force  yields  large 
quantities  of  fibrin  when  it  is  not  separated  from  a  substance 
which  precipitates  by  cooling  and  which,  on  microscopical  exami- 
nation, is  very  similar  to  Bizzozeeo's  blood-tablets.  Neverthe- 
less, as  Lowit  has  found  that  homogeneous  drops  may  exude  from 
the  white  blood-corpuscles  before  the  coagulation  which  take  a 
form  similar  to  tablets,  it  is  probable  that  the  substance  observed 
by  Wooldeidge  which,  on  cooling,  separates  as  a  formation 
similar  to  tablets  originates  from  the  colorless  blood-corpuscles. 
That  a  coagulation  without  a  destruction  of  the  colorless  blood- 
corpuscles  may  take  place  has  been  clearly  demonstrated  by 
Lowit,  who,  however,  does  not  dispute  the  importance  of  the 


92  PHYSIOLOQIOAL   CHEMISTRY. 

colorless  Dlood-corpuscles  in  the  coagulation.  On  the  contrary,  he 
has  observed  that  in  crab^s  blood  a  so-called  "  plasmoscJiise,"  which 
is  the  exit  of  constituents  of  the  cells  in  the  plasma,  takes  place 
before  the  coagulation,  and  this  process,  he  claims,  stands  in  close 
relationship  to  the  coagulation  of  the  blood.  If  we  do  not  give  too 
much  weight  to  the  destruction  of  the  leucocytes, — and  we  admit 
as  most  essential  this  part  of  Schmidt's  theory  that  the  impulse  to 
the  coagulation  comes  from  the  colorless  blood-corpuscles,  and  that 
the  constituents  of  the  same,  passing  into  the  plasma,  take  part  in 
the  coagulation, — then  Schmidt's  theory  is  not  disproved  by  the 
investigations  of  the  last  years,  but  it  is  even  supported  by  them. 

In  opposition  to  the  view  of  Alex.  Schmidt,  who  considers 
the  fibrin  coagulation  as  an  enzymotic  process,  Wooldkidge  is  of 
the  opinion  that  the  fibrin  ferment  is  not  the  cause  of  the  coagu- 
lation, but  is  a  product  of  the  chemical  processes  taking  place 
during  coagulation.  Wooldridge  claims,  on  the  contrary,  that 
lecithin  and  proteid  substances  containing  lecithin  are  of  the 
greatest  importance  in  the  coagulation.  This  product  is  obtained 
by  cooling  the  peptone-plasma  which  has  been  centrifu gated,  and 
the  substance  which  separates  has  been  called  by  Wooldridge 
^-fibrinogen.  The  plasma,  according  to  Wooldridge,  contains 
in  itself  all  qualities  necessary  to  produce  a  coagulation,  and  the 
form-elements  are  only  of  a  secondary  importance.  Peptone-plasma 
which  has  been  centrifugated  and  which  is  entirely  free  from  form- 
elements,  but  contains  the  ^-fibrinogen,  coagulates  on  diluting 
with  water,  by  the  passage  of  carbon  dioxide  through  the  liquid,  or 
after  the  addition  of  a  little  acetic  acid,  and  the  fibrin  ferment  is 
thereby  formed.  Wooldridge  designates  as  6-fibrinogen  the  ordi- 
nary fibrinogen  isolated  by  the  method  suggested  on  page  56.  This 
fibrinogen  occurs  indeed  in  transudations,  but  it  only  occurs  in  the 
peptone-plasma  in  very  small  quantities.  A  third  fibrinogen 
occurs  in  the  greatest  amounts  in  the  peptone-plasma,  and  this  is 
the  mother-substance  of  the  C-fibrinogen,  and  called  J5-fibrinogen 
by  Wooldridge.  The  ^-fibrinogen  is  converted  into  fibrin  by 
lecithin  and  leucocytes  from  the  lymphatic  glands,  but  not  by 
fibrin  ferment  or  blood-serum.  After  the  previous  action  of  serum 
or  fibrin  ferment  the  ^-fibrinogen  yields  fibrin  on  diluting  with 
water.     The  one  most  essential  for  the  fibrin  coagulation  is,  ac- 


THE  BLOOD.  '  93 

cording  to  Wooldkidge,  a  reciprocal  action  between  A-  and  B- 
fibrinogen.  An  exchange  of  lecithin  from  the  ^-fibrinogen  to  the 
^-fibrinogen  takes  place. 

Halliburton  has  opposed  weighty  arguments  to  this  theory. 
It  is  also  difficult  to  find  in  Wooldridge's  discussion  conclusive 
proofs  for  the  above  views,  and  the  experiments  by  which  they  are 
supported  are  interpreted  with  difficulty.  The  entire  theory  is 
chiefly  based  on  experiments  with  "peptone-plasma;"  but  such 
plasma  acts  differently  in  certain  respects  than  ordinary  plasma. 
It  should  be  especially  mentioned  that,  while  ordinary  plasma  and 
an  ordinary  fibrinogen  solution  act  similarly  on  heating,  the  pep- 
tone-plasma shows  quite  different  behavior.  The  peptone-plasma 
when  diluted  with  water,  or  on  passing  CO2  through  it,  or  on  the  ad- 
dition of  a  little  acid,  also  acts,  when  the  so-called  ^4 -fibrinogen  has 
not  been  removed,  like  a  plasma  in  which  the  ordinary  fibrinogen 
(C-fibrinogen)  has  been  partly  converted  into  an  intermediate  step 
between  fibrinogen  and  fibrin.  Until  the  differences  existing  be- 
tween ordinary  plasma  and  peptone-plasma  shall  have  been  more 
thoroughly  tested  and  generally  accepted  it  will  be  difficult  to  give 
an  unambiguous  interpretation  of  observations  made  on  peptone- 
plasma. 

Freund  seeks  the  reason  for  the  coagulation  in  a  separation 
of  calcium  phosphate  whereby  a  part  of  the  previously-dissolved 
albuminous  bodies  becomes  insoluble  as  fibrin.  By  the  adhesion 
existing  before  the  coagulation  the  alkali  phosphate  of  the  form- 
elements  passes  over  to  the  plasma  richer  in  lime  salts  and  forms 
calcium  phosphate.  If  the  amount  of  this  last  is  so  large  in  the 
plasma  or  any  other  coagulable  liquid  that  it  cannot  be  kept  com- 
pletely in  solution,  then,  according  to  Freukd's  views,  the  separa- 
tion of  the  excess  is  the  cause  of  a  part  of  the  albuminous  bodies 
becoming  insoluble,  or,  in  other  words,  is  the  cause  of  the  coagula- 
tion. It  is  a  well-known  fact  that  fibrin  and  fibi'inogen  yield  an 
ash  containing  calcium  phosphate,  and  that  lime  salts  facilitate 
coagulation  or  cause  a  coagulation  in  liquids  poor  in  ferment;  and 
it  is  also  well  known  that  rennet  ferment  cannot  cause  a  coagula- 
tion in  a  casein  solution  if  there  is  a  lack  of  lime  salts.  There  is 
no  question  about  the  lime  salts  being  of  great  importance  in  the 
fibrin  coagulation  ;  but  that  a  separation  of  calcium  phosphate  is 


94  PHYSIOLOGICAL  VREMISTRT. 

the  cause  of  coagulation  has  been  just  as  little  proved  as  the  asser- 
tion that  the  coagulation  of  milk  in  the  preparation  of  cheese  is 
produced  by  the  calcium  phosphate  becoming  insoluble  without 
the  action  of  the  rennet  ferment  on  the  casein.  The  untenability 
of  Feeund's  theory  has  been  shown  by  Latschenbergee. 

According  to  Dogiel  and  Holzman]S",  the  coagulation  of  the 
fibrin  is  an  oxidation  of  the  fibrinogen.  The  relation  of  oxygen  to  the 
coagulation  is  not  quite  clear;  a  certain  influence,  however,  on  the 
coagulation  cannot  be  denied.  But  as  the  coagulation  may  take 
place  also  in  the  absence  of  free  oxygen,  the  above  statement  seems 
not  to  be  well  grounded. 

The  very  dark  and  complicated  process  of  the  intravascular 
coagulation  and  the  relationship  of  the  so-called  tissue  fibrinogen 
(Wooldeidge)  to  the  same  have  been  so  insufficiently  studied  that 
we  cannot  enter  here  into  a  discussion  of  this  interesting  question. 

IV.  The  Gases  of  the  Blood. 

Since  the  pioneer  investigations  of  Magnus  and  Lothar 
Metee  the  gases  of  the  blood  have  been  subjects  for  repeated,  care- 
ful investigations  by  prominent  experimenters,  among  whom  we 
must  mention  first  C.  Ludwig  and  his  pupils  and  E.  Pflugee 
and  his  school.  By  these  investigations  not  only  has  science  been 
enriched  by  a  mass  of  facts,  but  also  the  methods  themselves  have 
been  made  more  perfect  and  accurate.  In  regard  to  these  methods, 
as  also  in  regard  to  the  laws  of  the  absorption  of  gases  by  liquids, 
dissociation,  and  other  questions  belonging  here,  the  reader  is 
referred  to  complete  text-books  on  physiology,  on  physics,  aud  on 
gasometric  analysis. 

The  gases  occurring  in  blood  under  physiological  conditions  are 
oxygen,  carlon  dioxide,  and  nitrogen.  The  last-mentioned  gas  is 
only  found  in  very  small  amounts,  on  an  average  of  1.8  vol.  per  cent. 
The  amount  is  here,  as  in  all  following  experiments,  calculated  for 
0°  C.  and  760  mm.  pressure.  The  nitrogen  seems  to  be  simply  ab- 
sorbed into  the  blood,  at  least  in  great  part.  It  appears  to  play  no 
part  in  the  processes  of  life,  and  its  amount  varies  but  slightly  in 
the  blood  of  different  blood-vessels. 

The  oxygen    and  carbon  dioxide  behave  otherwise,  as  their 


THE  BLOOD.  95 

amounts  have  significant  variations,  not  only  in  the  blood  from 
different  hlood-vessels,  but  also  because  many  conditions,  such  as  a 
difference  in  the  circulation,  a  different  temperature,  rest  and  ac- 
tivity, cause  a  change.  The  arterial  and  venous  blood  show  the 
greatest  difference  in  regard  to  the  gases  they  contain. 

The  amount  of  oxygen  in  the  arterial  blood  of  dogs  is  on  an 
average  22  vols,  per  cent  (Pfluger).  In  human  blood  SETSCHEisrow 
found  about  the  same  amount,  namely,  21.6  vols,  per  cent.  Lower 
figures  have  been  found  for  rabbit's  or  bird's  blood,  respectively 
13.2^  and  10-15^  (Walter,  Jolyet).  Venous  blood  has  very  vari- 
able amounts  of  oxygen.  Ludwig  and  Sczelkow  found  6.8^  oxy- 
gen in  the  venous  blood  of  quiet  muscles  and  a  still  smaller  amount 
in  the  venous  blood  of  active  muscles.  Oxygen  is  entirely  absent 
from  blood  after  asphyxiation,  or  only  occurs  as  traces.  The  venous 
blood  of  the  glands  seems,  on  the  contrary,  during  secretion  to  be 
richer  in  oxygen  than  ordinary  venous  blood.  By  summarizing  a 
great  number  of  analyses  by  different  experimenters,  Zuntz  has 
calculated  that  the  venous  blood  of  the  right  side  of  the  heart  con- 
tains on  an  average  7.15^  less  oxygen  than  the  arterial  blood. 

The  amount  of  carbon  dioxide  in  the  arterial  blood  of  dogs  is 
30  to  40  vols,  per  cent  (Ludwig,  Setschenow,  Pfluger,  P.  Bert, 
and  others),  most  generally  about  40^.  Setschenow  found  40.3 
vols,  per  cent  in  human  arterial  blood.  The  amount  of  carbon 
dioxide  in  venous  blood  varies  still  more  (Ludwig,  Pfluger  and 
their  pupils,  P.  Bert,  Mathieu  and  Urbaix,  and  others).  Accord- 
ing to  the  calculations  of  Zuntz  the  venous  blood  of  the  right  side 
of  the  heart  contains  about  8.2^  more  carbon  dioxide  than  the 
arterial.  The  average  amount  may  be  put  down  as  48  vols,  per  cent. 
Holmgrex  found  indeed  in  blood  after  asphyxiation  69.21  vols, 
per  cent  carbon  dioxide. 

Oxygen  is  absorbed  only  to  a  small  extent  by  the  plasma  or 
serum,  in  which  Pfluger  found  but  0.26^.  The  greater  part 
or  nearly  all  of  the  oxygen  is  loosely  combined  with  the  haemo- 
globin in  oxyhaemoglobin.  The  quantity  of  oxygen  which  is  con- 
tained in  the  blood  of  the  dog  corresponds  closely  to  the  quantity 
which  we  would  expect  from  the  activity  of  the  haemoglobin 
to  combine  with  oxygen,  and  also  the  quantity  of  hgemoglobin  in 
canine  blood.     It  is  difficult  to  ascertain  how  far  the  circulating 


96  PHY8I0L0QIGAL  CHEMI8TBT. 

arterial  blood  is  saturated  with  oxygen,  as  immediately  after  bleed- 
ing a  loss  of  oxygen  always  takes  place.  Still  it  seems  to  be  un- 
questionable that  it  is  not  quite  completely  saturated  with  oxygen 
in  life.  Arterial  canine  blood,  according  to  Pflugee,  is  saturated 
to  j9_  with  oxygen,  according  to  Hufjstee  to  ^|. 

The  question  whether  ozone  occurs  in  the  blood  is  to  be  answered 
decidedly  in  the  negative.  It  is  not  only  impossible  to  detect  ozone 
in  the  blood,  but  the  possibility  of  the  occurrence  of  ozone  in  the 
fluids  and  tissues  is  even  a  priori  to  be  denied.  Ozone  acts  as  nascent 
oxygen;  and  as  easily-oxidized  substances  occur  in  the  organism 
which  combine  with  nascent  oxygen,  ozone,  if  such  a  formation 
should  take  place  at  all,  would  be  destroyed  instantly.  But  such  a 
formation  of  ozone  in  the  animal  body  cannot  be  admitted.  Ozone 
may  indeed  be  formed  by  slow  oxidation,  since  the  nascent  oxygen 
formed  in  consequence  combines  with  neutral  oxygen  forming 
ozone;  but  in  the  animal  organism  the  nascent  oxygen  must  be 
bound  by  the  oxidized  substances  before  it  can  form  ozone. 

It  was  formerly  believed  that  the  haemoglobin  acted  as  an 
"  ozone-exciter,^'  possessing  the  property  of  converting  the  inactive 
oxygen  of  the  air  into  ozone.  The  red  blood-corpuscles  can  by 
themselves  also  give  a  blue  color  with  tincture  of  guaiacum,  which 
is  markedly  seen  when  this  tincture  is  dried  on  blotting-paper  and 
a  drop  of  blood  previously  diluted  with  5-10  vols,  water  is  added. 
According  to  Pfluger,  we  are  here  dealing  with  a  decomposition 
and  gradual  oxidation  of  haemoglobin,  in  which  processes  the  neu- 
tral oxygen  is  split,  setting  free  oxygen  atoms. 

The  carbon  dioxide  of  the  blood  occurs  in  part,  and  indeed,  ac- 
cording to  the  investigations  of  Alex.  Schmidt  and  L.  Fredbricq, 
generally  -g-  in  the  blood- corpuscles,  and  it  also  occurs  in  part,  and 
in  fact  the  greatest  part,  in  the  plasma  and  serum  respectively.  Of 
the  carbon  dioxide  in  the  form-elements  a  small  part,  according  to 
Setschenow,  occurs  in  the  colorless  corpuscles  (probably  combined 
with  the  globulin  alkali),  while  the  chief  mass  exists  in  the  red 
blood-corpuscles. 

The  carbon  dioxide  of  the  red  corpuscles  is  loosely  combined,  and 
the  constituent  uniting  with  the  CO3  of  the  same  seems  to  be  the 
alkali  combined  with  phosphoric  acid,  oxyhaemoglobin  or  haemoglobin 
and  globulin  on  one  side  and  the  haemoglobin  itself  on  the  other. 


THE  BLOOD.  97 

That  iu  the  red  corpuscles  alkali  phosphate  occurs  in  such  quanti- 
ties that  it  may  be  of  importance  in  the  combination  with  carbon 
dioxide  is  not  to  be  doubted,  and  we  must  admit  that  from  the 
diphosphate,  by  a  greater  partial  pressure  of  the  carbon  dioxide, 
monophosphate  and  alkali  carbonate  are  formed,while  by  a  lower  par- 
tial pressure  of  the  carbon  dioxide  the  mass  action  of  the  phosphoric 
acid  comes  again  into  play,  so  that  with  tlie  carbon  dioxide  becom- 
ing free,  a  re- formation  of  alkali  diphosphate  takes  place.  It  is 
generally  admitted  that  the  blood-coloring  matters,  especially  the 
oxyha^moglobiu,  which  can  expel  carbon  dioxide  from  sodium  car- 
bonates in  vacuo  (Preyer),  act  like  an  acid;  and  as  the  globulin  also 
acts  like  an  acid  (see  below),  this  body  may  also  occur  in  the  blood- 
corpuscles  as  alkali  combination.  The  alkali  of  the  blood-corpuscles 
must  therefore,  according  to  the  law  of  the  action  of  the  mass  be- 
tween the  carbon  dioxide,  phosphoric  acid,  and  the  others,  be  con- 
sidered as  active  acid  constituents  of  the  blood-corpuscles,  and  among 
these  especially  the  blood-coloring  matters,  as  the  globulin  can 
hardly  be  of  importance  because  of  its  small  quatitity.  By  greater 
mass-action  or  greater  partial  pressure  of  the  carbon  dioxide,  bicar- 
bonate must  be  formed  at  the  expense  of  the  diphosphates  and  the 
other  alkali  combinations,  while  at  a  diminished  partial  pressure  of 
the  same  gas,  with  the  escape  of  carbon  dioxide,  the  alkali  diphos- 
phate and  the  other  alkali  combinations  must  be  re-formed  at  the 
cost  of  the  bicarbonate. 

Haemoglobin  must  nevertheless,  as  the  investigations  of  Set- 
SCHENOW  and  Zuxtz  and  especially  those  of  Bohr  and  Torup 
have  shown,  be  able  to  hold  the  carbon  dioxide  loosely  combined 
even  in  the  absence  of  alkali.  Bohr  has  also  found  that  the  dis- 
sociation curve  of  the  carbon-dioxide  haemoglobin  corresponds 
essentially  to  the  curve  of  the  absorption  of  carbon-dioxide,  from 
which  ground  he  and  Torup  consider  the  hemoglobin  itself  as 
of  importance  in  the  binding  of  the  carbon  dioxide  of  the  blood 
and  not  its  alkali  combinations.  In  regard  to  this  question  the 
conditions  are  not  quite  clear.  If  carbon  dioxide  is  allowed  to  act 
on  haemoglobin,  it  unites  (Bohr,  Torup)  witn  the  colored  atomic 
group  of  the  haemoglobin,  splitting  off  albumin,  and  from  this 
haemoglobin,  so  decomposed,  oxyhfemoglobin  cannot  be  formed  by 
the  action  of  oxygen.     According  to   Bohr,  for  each  gramme  of 


98  PHYSIOLOGICAL  CHEMI8TBT. 

hsemoglobin  at  +  18.4°  C.  and  a  pressure  of  30  mm.  2.4  c.  cm.  carbon 
dioxide  are  combined ;  and  since  in  the  arterial  blood  nearly  all  the 
hgemoglobin  exists  as  oxyhaemoglobin,  it  is  difficult  to  obtain,  at 
least  from  the  arterial  blood,  an  appreciable  fraction  of  the  carbon 
dioxide  as  carbon-dioxide  haemoglobin.  It  cannot  be  denied  that  a 
not  insignificant  part  of  the  carbon  dioxide  of  the  blood  is  held  by 
the  red  corpuscles  in  loose  combination;  but  how  this  combination 
takes  place  requires  further  investigation  before  it  can  be  answered. 

The  chief  part  of  the  carbon  dioxide  of  the  blood  is  found  in  the 
blood-plasma  or  the  blood-serum_,  which  follows  from  the  fact  that 
the  serum  is  richer  in  carbon  dioxide  than  the  correspond- 
ing blood  itself.  By  experiments  with  the  air-pump  on  blood- 
serum  it  has  been  found  that  the  chief  part  of  the  carbon  dioxide 
contained  in  the  serum  is  given  off  in  a  vacuum,  while  a  smaller 
part  can  only  be  pumped  out  after  the  addition  of  an  acid.  The 
red  corpuscles  also  act  as  an  acid,  and  therefore  in  blood  all  the 
carbon  dioxide  is  expelled  in  vacuo.  A  part  of  the  carbon  dioxide 
is  firmly  chemically  combined  in  the  serum. 

Absorption  experiments  with  blood-serum  have  shown  us 
further  that  the  carbon  dioxide  which  can  be  pumped  out  is  in 
great  part  loosely  chemically  combined,  and  from  this  loose  combi- 
nation of  the  carbon  dioxide  it  necessarily  follows  that  the  serum 
must  also  contain  simply-absorbed  carbon  dioxide.  For  the  form 
of  binding  of  the  carbon  dioxide  contained  in  the  serum  or  the 
plasma  we  find  the  three  following  possibilities :  1.  A  part  of  the 
carbon  dioxide  is  simply  absorbed;  2.  Another  part  is  loosely 
chemically  combined;  and  3.  A  third  part  is  in  firm  chemical 
combination. 

The  quantity  of  simply-absorbed  carbon  dioxide  has  not  been 
exactly  determined.  Setschenow  considers  the  quantity  in  dog- 
serum  to  be  about  yV  of  the  total  quantity  of  carbon  dioxide. 
According  to  the  tension  of  the  carbon  dioxide  in  the  blood  and  its 
absorption  coefficient,  the  quantity  seems  to  be  still  smaller. 

The  quantity  of  firmly  chemically  combined  carbon  dioxide  in 
the  blood-serum  is  the  same  as  the  quantity  of  simple  alkali  carbon- 
ate in  the  serum.  This  quantity  is  not  known,  and  it  cannot  be 
determined  either  by  the  alkalinity  found  by  titration,  nor  can  it  be 
calculated  from  the  excess  of  alkali  found  in  the  ash,  because  the 


THE  BLOOD.  99 

alkali  is  not  only  combined  with  carbon  dioxide  but  also  with  other 
bodies,  especially  with  albumin.  The  quantity  of  firmly  chemically 
combined  carbon  dioxide  cannot  be  ascertained  after  pumping  out 
in  vacuo  without  the  addition  of  acid,  because  to  all  appearances 
certain  active  constituents  of  the  serum,  as  acids,  expel  carbon 
dioxide  from  the  simple  carbonate.  The  quantity  of  carbon 
dioxide  not  expelled  from  dog-serum  by  vacuum  alone  without  the 
addition  of  acid  amounts  to  4.9  to  9.3  vols,  per  cent,  according  to 
the  determinations  of  Pfluger. 

From  the  occurrence  of  simple  alkali  carbonates  in  the  blood- 
serum  it  naturally  follows  that  a  part  of  the  loosely-combined 
carbon  dioxide  of  the  serum  which  can  be  pumped  out  must  occur 
as  bicarbonate.  The  occurrence  of  this  combination  in  the  blood- 
serum  has  been  directly  shown.  In  experiments  with  the  pump, 
as  well  as  in  absorption  experiments,  the  serum  behaves  in  other 
ways  as  a  solution  of  bicarbonate,  or  carbonate  of  a  corresponding 
concentration;  and  the  behavior  of  the  loosely-combined  carbon 
dioxide  in  the  serum  can  be  explained  only  by  the  occurrence  of 
bicarbonate  in  the  serum.  By  means  of  vacuum  the  serum  always 
allows  much  more  than  one  half  of  the  carbon  dioxide  to  be  expelled, 
and  it  follows  from  this  that  in  the  pumping  out  not  only  may  a 
dissociation  of  the  bicarbonate  take  place,  but  also  a  conversion  of 
the  double  sodium  carbonate  into  a  simple  salt.  As  we  know  of  no 
other  carbon-dioxide  combination  besides  the  bicarbonate  in  the 
serum  from  which  the  carbon  dioxide  can  be  set  free  by  simple  dis- 
sociation in  vacuo,  we  are  obliged  to  assume  that  the  serum  must 
contain  other  faint  acids  in  addition  to  the  carbon  dioxide,  which 
contend  with  it  for  the  alkalies  and  which  expel  the  carbon  dioxide 
from  simple  carbonates  in  vacuo.  The  carbon  dioxide  which  is 
expelled  by  means  of  the  pump  and  which,  without  regard  to  the 
simple  absorbed  quantity,  is  generally  designated  as  "  loosely  chemi- 
cally combined  carbon  dioxide,"  is  thus  only  obtained  in  part  in 
dissociable  loose  combination;  in  part  it  originates  from  the  sim- 
ple carbonates,  from  which  it  is  expelled  in  vacuo  by  other  faint 
acids. 

These  faint  acids  are  thought  to  be  in  part  phosphoric  acid  and 
in  part  globulin.  The  importance  of  the  alkali  phosphates  for  the 
carbon  dioxide  combination  (see  page  97)  has  been  shown  by  the 


100  PHYSIOLOGICAL   CHEMISTRY. 

investigations  of  Fbenet;  but  the  quantity  of  these  salts  in  the 
serum  is,  at  least  in  certain  kinds  of  blood,  for  example  in  ox- 
serum,  so  small  that  it  can  hardly  be  of  importance.  In  regard  to 
the  globulins  Setschenow  is  of  the  opinion  that  they  do  not  act 
as  acids  themselves,  but  form  a  combination  with  carbon  dioxide, 
producing  carbogiobulinic  acid  which  unites  with  the  alkali.  Ac- 
cording to  Seetoli,  whose  views  have  lately  found  a  supporter  in 
ToRUP,  the  globulins  themselves  are  the  acids  combined  with  the 
alkali  of  the  blood-serum.  In  both  cases  the  globulin  would 
form,  directly  or  indirectly,  that  chief  constituent  of  the  plasma  or 
of  the  blood-serum  which,  according  to  the  law  of  the  action  of 
masses,  contends  with  the  carbon  dioxide  for  the  alkalies.  By  a 
greater  partial  pressure  of  the  carbon  dioxide  the  latter  deprives 
the  globulin  alkali  of  a  part  of  its  alkali,  and  bicarbonate  is  formed; 
by  low  partial  pressure  the  carbon  dioxide  escapes,  and  the  bicar- 
bonate is  taken  up  by  the  globulin  alkali. 

In  the  above  statements  it  has  been  emphasized  that  the  oxygen 
in  the  blood  occurs  in  a  dissociable  combination  with  the  haemo- 
globin, and  for  the  formation  of  this  combination,  the  oxyhsemo- 
globin,  a  certain  partial  pressure  of  the  oxygen  is  necessary  at  any 
temperature.  Also  the  carbon  dioxide  of  the  blood,  that  which  is 
contained  in  the  blood- corpuscles  as  well  as  that  in  the  plasma,  oc- 
curs mostly  in  combinations  which  are  dependent  to  a  "great  extent 
upon  the  partial  pressure  of  the  carbon  dioxide.  For  the  study  of 
the  exchange  of  gases  between  the  blood  and  the  alveolar  air  on 
one  side,  and  the  blood  and  the  tissues  on  the  other,  special  regard 
must  be  paid  to  the  question  as  to  how  far  this  exchange  of  gases 
is  the  result  of  the  law  of  diffusion  and  how  far  other  forces  take 
part  in  it;  also  the  tension  of  the  oxygen  and  the  carbon  dioxide 
is  of  the  greatest  importance. 

The  law  of  the  dissociation  of  oxyhasmoglobin  has  been  studied 
by  many  investigators.  Of  the  greatest  physiological  interest  are 
those  investigations  which  relate  to  the  dissociation  at  the  temper- 
ature of  the  body.  In  regard  to  these,  many  investigators  (P.  Bert, 
Herter,  and  Hufner)  have  found,  partly  by  experiments  on  the 
living  animal  and  partly  by  experiments  with  blood  or  pure  haemo- 
globin solutions,  that  the  tension  of  the  oxygen  of  the  blood  at  the 
temperature  of  the  body  corresponds  to  an  oxygen  partial  pressure 


THE  BLOOD.  101 

of  about  75-80  mm.  mercury.  Bohr  has  obtained  a  somewhat  differ- 
ent result  from  his  investigations.  He  experimented  on  dogs 
which  were  injected  with  leech  infusion  or  peptone  solution  so  as 
to  prevent  coagulation  of  the  blood,  and  he  allowed  the  blood  to 
circulate  through  an  apparatus  which  was  inserted  between  the 
central  and  peripheral  end  of  the  cut  carotid,  or  between  the  cen- 
tral end  of  the  carotid  and  the  central  end  of  the  cut  jugular  vein, 
and  in  this  way  the  exchange  of  gases  between  the  blood  and  a  gas 
mixture  of  known  constitution  could  be  determined.  As  measure 
of  the  tension  of  the  oxygen  in  the  arterial  blood  he  obtained  a  dis- 
proportionate high  value  or  an  average  pressure  of  136.5  mm.  mer- 
cury. By  a  simultaneous  determination  of  the  oxygen  tension  in 
the  blood  and  in  the  expired  air  of  the  same  animals  he  found  in 
several  cases  a  higher  value  for  the  former  than  for  the  latter. 
While  according  to  P.  Bert's  investigations  the  taking  up  of  oxy- 
gen from  the  air  of  the  lungs  by  the  blood  may  be  explained  by  the 
high  oxygen  partial  pressure  in  the  air  of  the  lungs,  this  is  not  per- 
ceptible according  to  the  experiments  of  Bohr,  in  which  the  ten- 
sion of  the  oxygen  in  the  blood  is  greater  than  in  the  expired  air, 
and  also  for  evident  reasons  it  is  still  greater  than  in  the  alveolar 
air.  Bohr  is  also  of  the  opinion  that  the  generally-accepted  diffu- 
sion theory  does  not  give  sufficient  explanation  for  the  taking  up 
of  oxygen  from  the  air,  and  that  we  must  also  admit  that  the  lung- 
tissue  itself  plays  an  active  part  in  the  taking  up  of  oxygen. 

As  the  chief  quantity  of  the  oxygen  in  the  blood  simply  ab- 
sorbed, corresponding  to  the  pressure,  is  contained  as  a  loose  chem- 
ical combination,  it  is  to  be  supposed  that  the  amount  of  oxygen  in 
the  blood,  at  least  within  certain  limits,  is  independent  of  the 
amount  of  oxygen  in  the  air. 

That  the  raising  of  the  oxygen  pressure,  even  to  a  pressure  of 
one  atmosphere,  has  no  essential  influence  on  the  amount  of  oxygen 
taken  up,  and  on  the  carbon  dioxide  eliminated,  has  been  known 
for  a  long  time  (Lavoisier,  Reonault,  and  Eeiset).  Further 
experiments  in  this  direction  have  been  made  by  Paul  Bert.  He 
found  that  in  pure  oxygen  at  a  pressure  of  3  atmospheres,  or  in  or- 
dinary air  at  a  pressure  of  15  atmospheres,  animals  quickly  died 
with  convulsions.  Before  and  during  the  spasms  a  lowering  of 
temperature  took  place,  and  the  consumption  of  oxygen,  as  well  as 


102  PHYSIOLOGICAL   CHEMISTRY. 

the  elimination  of  carbon  dioxide  and  the  combustion  of  the  sugar 
of  the  blood,  was  lowered.  By  raising  the  oxygen  pressure  of  the 
air  to  3  atmospheres  the  amount  of  oxygen  contained  in  the  blood 
is  somewhat  increased.  It  seems  that  the  amount  of  oxygen  which 
is  here  taken  up  corresponds  to  that  quantity  which  is  simply  ab- 
sorbed by  the  blood  at  that  pressure. 

It  is  also  of  special  interest  to  know  to  what  extent  the  partial 
pressure  of  the  oxygen  of  the  air  can  be  lowered  without  causing  any 
injurious  action  or  danger  to  life.  A  great  many  observations  have 
been  made  on  this  subject,  partly  on  man  (P.  Beet,  Sivel  and 
Oroce-Spinelli,  Leblanc,  and  others)  and  partly  on  animals  (by 
W.  Muller,  Hoppe-Setler,  Stroganov^^,  Beet,  Friedlaistder 
and  Herter,  Frankel  and  Geppert).  From  these  observations 
it  seems  that  the  partial  pressure  of  the  oxygen  in  the  atmosphere 
may  sink  to  one  half  without  causing  a  disturbance.  The  respira- 
tion is  hindered  by  an  oxygen  tension  of  7-8^  of  an  atmosphere, 
and  at  a  still  lower  tension  a  lowering  of  the  temperature  is  ob- 
served, lassitude,  inability  of  muscular  movement,  and  insensibility. 
At  an  oxygen  tension  which  corresponds  to  about  3-3.5^  of  an 
atmosphere,  death  occurs. 

In  regard  to  the  amount  of  oxygen  in  the  blood  at  lower  air- 
pressures,  the  observations  of  Frankel  and  Geppert  on  dogs  must 
be  mentioned.  At  an  air-pressure  of  410  mm.  mercury  the  amount 
of  oxygen  in  the  arterial  blood  was  normal;  at  an  air-pressure  of 
378-365  mm.  it  was  a  little  diminished,  and  only  at  a  lowering  of  the 
pressure  to  300  mm.  was  a  marked  decrease  of  the  oxygen  observed. 

The  tension  of  the  carbon  dioxide  in  the  blood  has  been  deter- 
mined in  different  ways  by  Pfluger  and  his  pupils,  "Wolfberg, 
Strassburg,  and  Nussbaum.  According  to  the  density  method, 
the  blood  is  allowed  to  flow  directly  from  the  artery  or  vein 
through  a  glass  tube  which  contains  a  gas  mixture  of  a  known 
constitution.  If  the  tension  of  the  carbon  dioxide  in  the  blood  is 
greater  than  the  gas  mixture,  then  the  blood  gives  up  carbon 
dioxide;  while  in  the  reverse  case  it  takes  up  carbon  dioxide  from 
the  gas  mixture.  The  analysis  of  the  gas  mixture  after  passing 
the  blood  through  it  will  also  decide  if  the  tension  of  the  carbon 
dioxide  in  the  blood  is  greater  or  less  than  in  the  gas  mixture;  and 
by  a  sufficiently  great  number  of  determinations,  especially  when 


THE  BLOOD.  103 

the  amount  of  carbon  dioxide  of  the  gas  mixture  corresponds  as 
nearly  as  possible  in  the  beginning  to  the  probable  tension  of  this 
gas  in  the  blood,  we  may  learn  the  tension  of  the  carbon  dioxide  in 
the  blood. 

According  to  this  method,  the  carbon-dioxide  tension  of  the 
arterial  blood  is  on  an  average  2.8^  of  an  atmosphere,  correspond- 
ing to  a  pressure  of  21  mm.  mercury  (Strassbukg).  In  the  blood 
from  the  pulmonary  alveoli  Nussbaum  found  a  carbon-dioxide  ten- 
ision  of  3.81^  of  an  atmosphere,  corresponding  to  a  pressure  of  28.95 
mm.  mercury.  Strassbukg,  who  experimented  on  tracheotomized 
dogs,  in  which  the  ventilation  of  the  lungs  was  less  active  and 
therefore  the  carbon  dioxide  was  removed  from  the  blood  with  less 
readiness,  found  in  the  venous  blood  of  the  heart  a  carbon-dioxide 
tension  of  5.4^  of  an  atmosphere,  corresponding  to  a  partial  pressure 
of  41.01  mm.  mercury. 

Another  method  is  the  catheterization  of  a  flap  of  the  lungs. 
By  the  introduction  of  a  catheter  of  a  special  construction  into  a 
branch  of  a  bronchia  the  corresponding  flap  of  the  lung  may  be 
hermetically  sealed,  while  in  the  other  flaps  of  the  same  lung  and 
in  the  other  lung  the  ventilation  remains  unhindered,  so  that  no 
stowing  of  carbon  dioxide  takes  place  in  the  blood.  When  the 
cutting  off  lasts  so  long  that  a  complete  equalization  between  the 
gases  of  the  blood  and  the  cut-off  air  of  the  lungs  is  assumed,  a 
sample  of  this  air  of  the  lungs  is  removed  by  means  of  the  catheter 
and  analyzed.  In  the  air  thus  obtained  from  the  lungs  Nussbaum 
and  Wolfberg  found  an  average  of  3.6y^  CO^.  Nussbaum  has 
also  determined  the  carbon-dioxide  tension  in  the  blood  of  the 
pulmonary  alveoli  in  a  case  simultaneous  with  the  catheterization 
of  the  lungs.  He  found  nearly  identical  results,  namely,  a  carbon- 
dioxide  tension  of  3.84^  and  3.81^  of  an  atmosphere. 

While  according  to  the  just-mentioned  determinations  the  car- 
bon-dioxide pressure  in  the  venous  blood  amounts  to  about  30  mm. 
mercury  and  in  the  arterial  to  about  20  mm.,  Bohr  has,  on  the  con- 
trary, according  to  the  above-described  methods  (page  101),  found 
strikingly  lower  figures — 2  to  3  mm.,  and  even  lower  than  1  mm. 

The  quantity  of  carbon  dioxide  in  the  expired  air  amounts  to 
about  2.8^  (Wolfberg,  Bohr).  The  air  of  the  alveolus  of  the 
lungs  is  naturally  richer  in  carbon  dioxide,  but  the  amount  is  not 


104  PHTSIOLOGICAL    CHEMISTRY. 

exactLy  known.  If  we  start  from  the  figures  for  the  carbon-dioxide 
tension  fonnd  by  Pfluger  and  his  pupils,  and  when  we  recall,  fur- 
ther, that  XussBAUM  found  in  the  cut-off  air  of  the  lungs — which 
is  more  likely  to  be  richer  than  poorer  in  carbon  dioxide  than  the 
normal  alveolar  air  of  the  lungs — the  same  carbon-dioxide  tension 
as  in  the  venous  blood  of  the  heart,  then  these  observations  easily 
agree  with  the  view  that  elimination  of  the  carbon  dioxide  from 
the  blood  in  the  lungs  simply  follows  the  laws  of  diffusion. 
According  to  the  experiments  of  Bohe,  in  which  the  blood  and 
the  expired  air  were  investigated  at  the  same  time,  and  in  which 
he  found  the  carbon-dioxide  tension  in  the  blood  significantly 
lower  than  the  expired  air — and  also  lower  than  the  alveolar  air, — 
such  an  assumption  as  the  above  is  impossible.  Bohr  also  wishes 
to  give  by  his  experiments  a  proof  of  the  view  suggested  long  ago 
by  Ludwig's  school,  namely,  that  the  lungs  play  a  specific  secre- 
tory role  in  the  elimination  of  carbon  dioxide.  The  necessity  of 
further  investigations  for  the  explanation  of  the  reason  for  these 
very  deviating  results  obtained  by  different  investigators  is  ap- 
parent. 

As  the  carbon  dioxide  is  always  in  part  combined  chemically, 
and  as  this  part  increases  with  the  amount  of  alkali  in  the  blood, 
it  is  evident  that  the  amount  of  carbon  dioxide  and  the  carbon- 
dioxide  tension  must  not  always  be  parallel.  That  this  is  a  fact 
has  been  shown  by  Gaule  in  experimenting  on  suffocated  dogs. 
If  the  amount  of  alkali  in  the  blood  be  diminished,  then,  naturally, 
the  amount  of  carbon  dioxide  will  be  decreased.  Such  a  behavior 
is  found  in  poisoning  by  mineral  acids.  Walter  found  only  2-3 
vols,  per  cent  carbon  dioxide  in  the  blood  of  a  rabbit  which  had 
hadrvhydrochloric  acid  introduced  into  the  stomach.  In  the  coma- 
tose state  of  dioMtes  melitvs  the  alkali  of  the  blood  seems  to  be 
saturated  in  great  part  by  an  acid  combination  (^  oxy butyric  acid) 
(Stadelmaxx,  Minkowsky),  and  correspondingly  Mixkowskt 
found  in  the  blood  in  comatose  diabetes  only  3.3  vols,  per  cent 
carbon  dioxide. 

In  regard  to  the  carbon-dioxide  tension  in  the  tissue,  we  must 
assume  a  priori  that  it  is  higher  than  in  the  blood.  This  is  found 
to  be  true.  Strassburg  found  in  the  urine  of  dogs  and  in  the  bile 
a  carbon-dioxide  tension  of  9^  and  T,^  of  an  atmosphere,  respect- 


THE  BLOOD.  105 

ively.  The  same  experimenter  has,  further,  injected  atmospheric 
air  into  a  loosened  intestinal  knot  of  a  living  dog,  and  analyzed  the 
au'  taken  out  after  some  time.  He  found  a  carbon-dioxide  tension 
of  7.7,'^  of  an  atmosphere.  The  carbon-dioxide  tension  in  the  tissue 
is  strikingly  greater  than  in  venous  blood,  even  if  we  use  as  basis 
for  our  calculation  the  tigures  found  by  Pflugek  and  his  pupils,  as 
opposed  to  Bohr's  results  of  relatively  high  values,  for  the  carbon- 
dioxide  tension.  It  is  not  disputed  that  the  carbon  dioxide  simply 
passes  from  the  tissue  to  the  blood  according  to  the  laws  of 
diffusion. 


V.  The  Quantitative  Constitution  of  the  Blood. 

The  quantitative  analysis  of  blood  cannot  be  of  value  for  the  blood 
as  an  entirety.  We  must  ascertain  on  one  side  the  relationship  of 
the  plasma  and  blood-corpuscles  to  each  other,  and  on  the  other  side 
the  constitution  of  each  of  these  two  chief  constituents.  The  diffi- 
culties which  stand  in  the  way  of  such  a  task,  especially  in  regard 
to  the  living,  non-coagulated  blood,  have  not  been  removed.  JSince 
the  constitution  of  the  blood  may  differ  not  only  in  different  vas- 
cular regions,  but  also  in  the  same  region  under  different  circum- 
stances, which  renders  also  number  of  blood  analyses  necessary,  it 
can  hardly  appear  remarkable  that  our  knowledge  of  the  con 
stitution  of  the  blood  is  still  relatively  limited. 

If  any  substance  is  found  in  the  blood  which  belongs  exclusively 
to  the  plasma  and  does  not  occur  in  the  blood-corpuscles,  then  the 
amount  of  plasma  contained  in  the  blood  may  be  calculated  if  we 
determine  the  amount  of  this  substance  in  100  parts  of  the  plasma 
and  serum,  respectively,  on  one  side  and  in  100  parts  of  the  blood 
on  the  other.  If  we  represent  the  amount  of  this  substance  in  the 
plasma  by  p  and  in  the  blood  by  h,  then  the  amount  x  of  the  plasma 

in  100  parts  of  blood  is    a:  = '- — . 

p 

Such  a  substance,  which  occurs  only  in  the  plasma,  is  fibrin 
according  to  Hoppe-Setler,  sodium  according  to  Bunge  (in  cer- 
tain kinds  of  blood),  and  sugar  according  to  Otto.  The  experi- 
menters just  named  have  tried  to  determine  the  amount  of  the 
plasma  and  the  blood-corpuscles,  respectively,  in  different  kinds 
of  blood,  starting  from  the  above-mentioned  substances. 


106 


PHYSIOLOOICAL  CHEMISTRY. 


Another  method,  suggested  by  Hoppe-Seyler,  is  to  determine 
the  total  amount  of  hemoglobin  and  albumin  in  a  portion  of  blood, 
and  on  the  other  hand  the  amount  of  hsemoglobin  and  albumin  in 
the  blood-corpuscles  of  an  equal  portion  of  the  same  blood  which 
have  been  sufficiently  washed  with  common-salt  solution  by  centrif- 
ugal force.  The  figures  obtained  as  a  difference  between  these  two 
determinations  correspond  to  the  amount  of  albumin  which  was 
contained  in  the  serum  of  the  first  portion  of  blood.  If  we  now 
determine  the  albumin  in  a  special  portion  of  serum  of  the  same 
blood,  then  the  amount  of  serum  in  the  blood  is  easily  determined. 
The  usefulness  of  this  method  has  been  confirmed  by  Bunge  by 
the  control  experiments  with  the  sodium  determinations.  If  the 
amount  of  serum  and  blood-corpuscles  in  the  blood  is  known,  and 
we  then  determine  the  amount  of  the  different  blood-constituents 
in  the  blood-serum  on  one  side  and  of  the  total  blood  on  the 
other,  the  distribution  of  these  different  blood-constituents  in  the 
two  chief  components  of  the  blood,  plasma  and  blood-corpuscles 
may  be  ascertained.  According  to  the  just-mentioned  procedure, 
the  following  analyses  of  pig's  blood  and  ox's  blood  have  been  made 
by  BuNGE.  Analyses  of  human  blood  have  been  made  for  some 
time  by  C.  Schmidt  according  to  another  method,  which  perhaps 
have  given  rather  too  high  results  for  the  weight  of  the  blood- 
corpuscles.     All  figures  represent  parts  in  1000  parts  of  blood. 


Pig's  Blood. 

Ox's  Blood. 

Human  Blood. 

Man's. 

Woman's. 

Blood- 
cor- 
puscles 
436.8 

Serum 
563.2 

Blood- 
cor- 
puscles 
318.7 

Serum 
681.3 

Blood- 
cor- 
puscles 
513.02 

■ 

Serum 
486.98 

Blood- 
cor- 
puscles 
396.24 

Serum 
603.76 

Water 

276.100 
160.700 

151.600 

5.200 
3.900 
2.421 

517.900 
45.300 

38.100 

2.800 
4.300 
0.154 
2.406 
0.072 
0.021 
0.006 
2.034 
0.106 

191.200 
127.500 

123.600 

2.400 
1.500 
0.238 
0.667 

"b'.m 
'b'.m 

0.224 

622.200 
59.100 

49.900 

3.800 
5,400 
0.173 
2.964 
0.070 
0.031 
0.007 
2.532 
0.181 

349.690 
163.330 

[159.590 

3.740 
1.586 
0.241 

439.020 
47.690 

43.820 

4.140 
0.153 
1.661 

272.560 
123.680 

120.130 

3.550 
1.412 
0.648 

551.990 

Solids 

Hsemoglobin  and  | 
Albumin               f 
Remaining  org.  bodies . 

Inorganic  bodies 

K2O 

NajO 

51.770 

46.700 

5.070 
0.200 
1.916 

CaO        

MgO  

0.069 

FPnOo                           

cf'  '..v.:::.::::;::::: 

0.657 
0.903 

0.898 
0.695 

1.722 
0.071 

0.362 
0.643 

0.144 

PjOb 

2.202 

Hoppe-Sbyler,  Sacharjin,  and  Otto  found  584.9-693.5  p.  m. 
plasma  and  415.1-306.5  p.  m.  blood-corpuscles  in  horse's  blood. 
BuNGE  found,  on  the  contrary,  in  an  analysis  468.5  p.  m.  serum 
and  531.5  p.  m.  blood-corpuscles — more  blood-corpuscles,  therefore, 


THE  BLOOD.  107 

than  serum.  For  human  blood  Arronet  has  found  478.8  p.  m. 
blood -corpuscles  and  521.2  p.  m.  serum  (in  defibrinated  blood)  as 
an  average  of  nine  determinations. 

The  relative  amount  of  blood-corpuscles  and  plasma  therefore 
varies.  In  human  blood  the  plasma  is  about  50^  of  the  weight  of 
the  blood;  but  in  other  cases  it  seems  generally  to  be  somewhat 
greater.  In  a  few  cases  it  may  indeed  be  f  of  the  weight  of  the 
blood.  Water  occurs  in  the  greatest  amount  in  the  plasma  or  serum, 
which  latter  ordinarily  contains  at  least  j^.  water,  while  the  blood- 
corpuscles  contains  only  a  little  more  than  |  or  about  f  water. 
Iron  probably  occurs  only  in  the  blood-corpuscles.  Chlorine  and 
sodium  prevail  generally  in  the  plasma,  potassium  and  phosphoric 
acid  in  the  blood-corpuscles.  In  a  few  varieties  of  blood  (pig^s 
and  horse's  blood)  the  sodium  is  found  exclusiv^ely  in  the  plasma  or 
serum,  the  potassium  prevailing  in  the  blood-corpuscles  (Bun^ge). 
In  dog's  and  ox's  blood  the  blood-corpuscles  are,  however,  richer 
in  sodium  than  in  potassium  (Bunge).  In  man  the  potassium 
is  contained  in  the  largest  quantities  in  the  blood-corpuscles 
and  only  in  very  small  quantities  in  the  plasma  (C.  Schmidt, 
Wanach).  The  alkaline  earths  occur  chiefly  in  the  plasma. 
Manganese  has  also  been  found  in  the  blood  (0.06  p.  m.  according 
to  Burin  de  Buisson),  as  well  as  traces  of  lithium,  copper,  lead,  and 
silver.  The  blood  as  a  whole  contains  in  ordinary  cases  770-820 
p.  m.  water,  with  180-230  p.  m.  solids;  of  these  173-220  p.  m. 
are  organic  and  6-10  p.  m.  inorganic.  The  organic  consist,  de- 
ducting 6-12  p.  m.  extractive  bodies,  of  albumin  and  haemoglobin. 
The  amount  of  these  last-mentioned  bodies  in  the  blood  is  about 
130-150  p.  m. 

The  amount  of  sugar  in  the  blood  is  on  an  average  1-1.5  p.  m. 
The  quantity  of  urea,  which  amounts  to  0.2-0.9  p.  m.,  is  greater 
after  partaking  of  food  than  during  fasting  (Grehant  and  Quin- 
QUAUd).  The  quantity  of  uric  acid  may  be  0.1  p.  m.  in  bird's  blood 
(v.  Schroder),  and  the  quantity  of  lactic  acid  may  reach  0,71  p. 
m.  in  human  venous  blood  (Berlinerblau). 


108  PRTSIOLOQICAL   CHEMISTRY. 

The  Constitution  of  the  Blood  in  different  Vascular  Regions  and 
under  different  Physiological  Conditions. 

Arterial  and  Venous  Blood.  The  most  striking  dijfference  be- 
tween these  two  kinds  of  blood  is  the  variation  in  color  caused  by 
their  containing  different  amounts  of  gas  and  different  amounts  of 
oxyhemoglobin  and  haemoglobin.  The  arterial  blood  is  light  red; 
the  yenous  blood  is  dark  red,  dichroitic,  gTeenish  by  transmitted 
light  through  thin  layers.  The  arterial  coagulates  more  quickly 
than  the  venous  blood.  The  latter,  on  account  of  the  transudation 
which  takes  place  in  the  capillaries,  is  somewhat  poorer  in  water 
but  richer  in  blood-corpuscles  and  hemoglobin  than  the  arterial 
blood  (Heidenhaix,  Nasse,  Otto).  The  quantity  of  sugar  is 
somewhat  greater  in  the  arterial  blood  than  in  the  venous  (Otto). 

Blood  from  the  Portal  Vein  and  the  Hepatic  Vein.  The  blood  of 
the  hepatic  vein  is  poorer  in  ordinary  red  blood-corpuscles  but  richer 
in  colorless  and  so-called  young  red  blood-corpuscles.  A  few  investi- 
gators have  decided  from  this  that  a  formation  of  red  blood-corpus- 
cles takes  j)lace  in  the  liver,  while  others  claim  that  a  destruction 
takes  place. 

In  consideration  of  the  relationship  to  the  simultaneous  forma- 
tion of  small  quantities  of  bile  and  lymph  in  the  unit  of  time  of 
the  large  quantities  of  blood  circulating  throuhg  the  liver  we  can 
hardly  expect  to  detect  a  positive  difference  in  the  constitution  of 
the  blood  of  the  hepatic  vein  by  chemical  analysis.  The  statements 
in  regard  to  such  a  difference  are  in  fact  contradictory.  For 
example,  Deosdofe  has  found  more  hsemoglobin  in  the  hepatic 
tlian  in  the  portal  veins,  while  Otto  found  less.  In  regard  to  the 
different  amounts  of  sugar  in  these  two  kinds  of  blood  we  have 
also  much  contradiction.  According  to  a  few  experimenters,  as 
Otto  and  above  all  others  SEEGEif,  the  blood  of  the  hepatic  vein  is 
richer  in  sugar,  which  corresponds  with  the  older  statements  of 
Claude  Bernard.  Such  a  difference  may,  however,  be  caused  by 
the  operative  interference  in  the  collection  of  the  blood  from  the 
liepatic  vein  (Abeles),  and  as  a  i-ule  investigators  nowadays  do  not 
seem  to  agi*ee  with  Bern"ard's  view.  During  the  digestion  of  food 
rich  in  carbohydrates  the  blood  of  the  portal  vein  may  not  only  be 
richer  in  glucose  but  also  contain  other  carbohydrates  (v.  Mertng. 


THE  BLOOD.  109 

Otto).  The  amount  of  urea  in  the  blood  from  the  hepatic  vein  is 
greater  than  in  other  blood  (Geehant  and  Quinquaud), 

Blood  of  the  Splenic  Vein  is  decidedly  richer  in  leucocytes 
than  the  blood  from  the  splenic  artery.  The  red  blood-corpuscles 
of  the  blood  from  the  splenic  vein  are  smaller  than  the  ordinary, 
less  flattened,  and  show  a  greater  resistance  to  water.  The  blood 
from  the  splenic  vein  is  also  claimed  to  be  richer  in  water,  fibrin,  and 
albumin  than  the  ordinary  venous  blood  (Beclard).  According  to 
V.  MiDDENDORFF,  it  is  richer  in  hsemoglobin  than  arterial  blood.  It 
coagulates  more  slowly. 

The  Blood  from  the  Veins  of  the  Glands.  The  blood  circulates 
with  greater  rapidity  through  a  gland  during  activity  (secretion) 
than  when  at  rest,  and  the  outflowing  venous  blood  has  therefore 
during  activity  a  lighter  red  color  and  a  greater  amount  of  oxygen. 
Because  of  the  secretion  the  venous  blood  also  becomes  somewhat 
poorer  in  water  and  richer  in  solids. 

The  blood  from  the  Muscular  Veins  shows  an  opposite  behavior, 
for  during  activity  it  is  darker  and  more  venous  in  its  properties 
because  of  the  increased  absorption  of  oxygen  by  the  muscles  or 
still  greater  production  of  carbon  dioxide  than  when  at  rest. 

Menstrual  Blood  has,  according  to  an  old  statement,  not  the 
power  of  coagulating.  This  statement  is  nevertheless  false,  and  the 
apparent  uncoagulability  depends  in  part  on  the  womb  and  the 
vagina  retaining  the  blood-clot,  so  that  only  fluid  cruor  is  at  times 
eliminated,  and  in  part  on  a  contamination  with  vaginal  mucus 
which  disturbs  the  coagulation. 

The  Blood  of  the  Two  Sexes.  Woman's  blood  coagulates 
somewhat  more  quickly,  has  a  lower  specific  gravity,  a  greater 
amount  of  water,  and  a  smaller  quantity  of  solids  than  the  blood 
of  man.  The  amount  of  blood-corpuscles  and  haemoglobin  is 
somewhat  smaller  in  woman's  blood.  The  amount  of  hsemoglobin 
is,  according  to  Otto,  146  p.  m.  for  man's  blood  and  133  p.  m.  for 
woman's. 

During  pregnancy  Nasse  has  observed  a  decrease  in  the  specific 
gravity,  with  an  increase  in  the  amount  of  water  towards  the  end  of 
the  eighth  month.  From  then  the  specific  gravity  increases,  and 
at  delivery  it  is  normal  again.  The  amount  of  fibrin  is  somewhat 
increased   (Becquerel  and   Rodier,   Nasse).      The   number   of 


110  PHYSIOLOGICAL   CHEMISTRY. 

blood-corpuscles  seems  to  decrease.  In  regard  to  the  amount  of 
haemoglobin  the  statements  are  somewhat  contradictory. 

The  Blood  at  Different  Periods  of  Life.  Foetal  blood  is 
strikingly  poorer  in  blood-corpuscles  and  haemoglobin  than  the 
blood  of  the  adult.  The  foetal  blood  at  the  moment  of  birth  has, 
according  to  Schereekziss,  a  lower  specific  gravity,  a  mark- 
edly lower  amount  of  haemoglobin,  and  a  little  less  fibrin,  but  a 
Greater  amount  of  mineral  bodies,  especially  proportionally  more 
sodium  (but  less  potassium)  than  the  blood  of  adults.  A  few. 
hours  after  birth  the  blood  of  the  child  has  the  same  quantity  of 
hemoglobin  as  the  blood  of  the  mother  (CoHiq-STEiif,  Zuktz,  Otto). 
The  amount  of  haemoglobin  and  of  blood-corpuscles  then  quickly 
increases;  still  they  do  not  both  increase  at  the  same  rate,  as  the 
amount  of  haemoglobin  increases  much  faster.  Two  to  three  days 
after  birth  the  hagmoglobin  reaches  a  maximum  (20-21^),  which  is 
greater  than  at  any  other  period  of  life.  This  is  the  cause  of  the 
great  abundance  of  solids  in  the  blood  of  new-born  infants  as 
observed  by  Denis,  Panum,  and  other  investigators.  The  quan- 
tity of  hgemoglobin  and  blood-corpuscles  sinks  gradually  from  this 
first  maximum  to  a  minimum  of  about  11,^  haemoglobin,  which 
minimum  appears  in  human  beings  between  the  fourth  and  eighth 
year.  The  quantity  of  haemoglobin  then  increases  again  until  about 
the  twentieth  year,  when  a  second  maximum  of  13.7-15^  is  reached. 
The  haemoglobin  remains  at  this  point  only  towards  the  forty-fifth 
year,  and  then  gradually  and  slowly  decreases  (Leichtensteen, 
Otto).  According  to  older  statements,  the  blood  at  old  age  is 
poorer  in  blood-corpuscles  and  albuminous  bodies  but  richer  in 
water  and  salts. 

Tlie  Influence  of  Food  on  the  Blood.  In  complete  starvation  a 
decrease  in  the  amount  of  solid  blood  constituents  is  found  to  take 
place  (Panum  and  others).  The  amount  of  haBmoglobin  is  a  little 
increased  (Subbotin,  Otto),  and  also  the  number  of  red  blood-cor- 
puscles is  greater  (Woem  Mullee,  Buntzen),  which  probably 
depends  on  the  fact  that  the  blood-corpuscles  are  not  so  quickly 
transformed  as  the  serum.  As  after-effect  the  inanition  causes  an 
anaemic  condition  (Woem  Mitllee,  Otto,  Buntzex). 

After  a  rich  meal  the  relative  number  of  blood-corpuscles, 
especially   after    secretion    of   digestive    juices    or    absorption    of 


THE  BLOOD.  Ill 

nutritive  liquids,  may  be  increased  or  diminished  (Buntzen", 
Leichtenstern).  The  number  of  colorless  blood-corpuscles  may- 
be increased  to  such  an  extent,  after  a  diet  rich  in  albumin,  that  a 
true  digestion  leucocytose  appears  (Hofmeistek  and  Pohl).  After 
a  diet  rich  in  fat  the  plasma  becomes,  even  after  a  short  time,  more 
or  less  milky-white,  like  an  emulsion.  The  constitution  of  the 
food  acts  essentially  on  the  amount  of  haemoglobin  in  the  blood. 
The  blood  of  herbivora  is  generally  poorer  in  haemoglobin  than 
that  from  carnivora,  and  Subbotin  has  observed  in  dogs  after  a 
partial  feeding  with  food  rich  in  carbohydrates  that  the  amount  of 
haemoglobin  sank  from  the  physiological  average  of  137.5  p.  m.  to 
103.2-93.7  p.  m.  According  to  Leichtenstern,  a  gradual  increase 
in  the  amount  of  haemoglobin  is  found  to  tak,e  place  in  the  blood 
of  human  beings  on  enriching  the  food,  and  according  to  the  same 
investigator  the  blood  of  lean  persons  is  generally  somewhat  richer 
in  haemoglobin  than  blood  from  fat  ones  of  the  same  age.  The 
addition  of  iron  salts  to  the  food  greatly  influences  the  number 
of  blood-corpuscles  and  also  the  amount  of  haemoglobin  they  con- 
tain, so  that,  according  to  Nasse,  the  iron,  especially  in  combination 
with  fat,  is  active.  According  to  the  investigations  of  Hayem  and 
Mallassez,  the  iron  preparations  increase  the  amount  of  haemo- 
globin contained  in  the  blood  in  anaemia  to  a  higher  degree  than 
the  number  of  blood-corpuscles. 

The  Constitution  of  the  Blood  under  Physiological  Conditions 
may  be  changed  either  by  the  appearance  of  a  foreign  substance  or 
by  the  quantities  of  any  one  or  more  of  the  blood  constituents 
being  abnormally  increased  or  diminished.  Changes  of  this  last 
kind  occur  frequently. 

An  i7icrease  in  the  mimber  of  red  corpuscles,  a  true  "  plethora 
POLTCYTHiEMiCA,"  takes  placc  after  transfusion  of  blood  of  the 
same  species  of  animal.  According  to  the  observations  of  Panum 
and  AVoRM  Muller,  the  blood-liquid  is  quickly  eliminated  and 
transformed  in  this  case, — the  water  being  eliminated  principally 
by  the  kidneys,  and  the  albumin  burned  into  urea,  etc., — while  the 
blood-corpuscles  are  preserved  longer  and  cause  a  "  polyctth^e- 
MiA."  A  relative  increase  in  the  number  of  red  corpuscles  is 
found  after  abundant  transudations  from  the  blood,  as  in  cholera 
and  heart-failure,  with  considerable  accumulation. 


112  PHYSIOLOGICAL  CHEMISTRY. 

A  decrease  in  the  number  of  red  corpuscles  occurs  in  anaemia 
from  different  causes.  Each  hemorrhage  causes  an  acute  angemia 
or  oligaemia.  Even  during  the  bleeding  the  remaining  blood  be- 
comes richer  in  water  by  diminished  secretion  and  excretion^  as 
also  by  an  abundant  absorption  of  parenchymous  fluid  somewhat 
poorer  in  albumin  and  strikingly  poorer  in  red  blood-corpuscles. 
The  oligsemia  passes  soon  into  a  hydremia.  The  amount  of  albumin 
then  gradually  increases  again;  but  the  re-formation  of  the  red 
blood-corpuscles  is  slower,  and  after  the  hydrgemia  follows  also  an 
oligocythsemia.  After  a  little  time  the  number  of  blood-corpuscles 
rises  to  normal;  but  the  re-formation  of  haemoglobin  does  not  keep 
pace  with  the  re-formation  of  the  corpuscles,  and  a  chlorotic  con- 
dition may  appear  (Laache,  Buntzen,  Otto).  A  considerable 
decrease  in  the  number  of  red  corpuscles  occurs  also  in  chronic 
anasmia  and  chlorosis;  still  in  such  cases  an  essential  decrease  in 
the  amount  of  haemoglobin  occurs  without  an  essential  decrease  in 
the  number  of  blood-corpuscles.  The  decrease  in  the  amount  of 
haemoglobin  is  more  characteristic  of  chlorosis  than  a  decrease  in 
the  number  of  red  corpuscles. 

A  very  considerable  decrease  in  the  number  of  red  corpuscles 
(from  300,000  to  iOO,000  in  1  c.  mm.)  and  diminishing  in  the  amount 
of  haemoglobin  (from  I  to  -^q)  occurs  in  malignant  anaemia  (Hayem, 
Lepine,  Laache,  and  others).  On  the  contrary,  the  individual 
red  corpuscles  are  larger  and  richer  in  hsemoglobin  than  they  ordi- 
narily are,  and  the  number  stands  in  an  inverse  relationship  to  the 
amount  of  haemoglobin  (Hatem). 

,  The  Constitutioji  of  the  Red  Corpuscles.  Irrespective  of  the 
changes  in  the  amount  of  haemoglobin,  as  just  mentioned,  the  con- 
stitution of  the  blood-corpuscles  may  be  changed  in  other  ways. 
By  abundant  transudation,  as  in  cholera,  the  blood-corpuscles  may 
give  up  water,  potassium,  and  phosphoric  acid  to  the  concentrated 
plasma  and  become  correspondingly  richer  in  organic  substances 
(C.  Schmidt).  By  a  few  other  transudations  processes,  as  in  dys- 
entery and  dropsy  with  albuminuria,  a  considerable  amount  of 
albumin  passes  from  the  blood,  the  plasma  becomes  richer  in  water, 
and  the  blood-corpuscles  may  take  up  water  and  so  become  poorer 
in  organic  substance  (C.  Schmidt). 

The   number   of  colorless   bluod-corpuscles  is   found   to  be  in- 


THE  BLOOD.  113 

creased  by  suppuration  in  puerperal  fever,  pygemia,  and  many 
other  diseases,  but  especially  in  leucasniia,  which  disease  is  char- 
acterized by  a  great  abundance  of  leucocytes  in  the  blood.  The 
number  of  leucocytes  is  not  only  absolutely  increased  in  this 
disease,  but  also  in  proportion  to  the  number  of  red  blood-cor- 
puscles, which  is  considerably  diminished  in  leucaemia.  The  blood 
from  a  leucsemic  patient  has  a  lower  specific  gravity  than  the  ordi- 
nary (1.035-1.040)  and  a  lighter  color,  as  if  it  were  mixed  with  pus. 
The  reaction  after  death  is  often  acid,  probably  due  to  a  decompo- 
sition of  the  considerably-increased  lecithin.  In  leuc^mic  blood, 
volatile  fatty  acids,  lactic  acid,  glycero-phosphoric  acid,  large 
amounts  of  xanthin  bodies  (Salomon,  Kossel)  and  the  so-called 
Charcot's  crystals  (see  Chapter  XI)  have  been  found. 

The  quantity  of  water  in  the  blood  is  increased  by  general 
dropsy,  with  or  without  kidney  disease,  by  the  different  forms  of 
anaemia,  by  scurvy,  and  by  febrile  diseases.  The  amount  of  water 
is  diminished  by  abundant  transudations,  by  powerful  laxatives,  by 
diarrhoea,  and  especially  by  cholera. 

The  amount  of  albumins  in  the  blood  may  be  relatively  in- 
creased (hyperalbuminose)  in  cholera  and  after  the  action  of 
laxatives.  A  decrease  in  the  amount  of  albumin  (hypalbuminose) 
occurs  after  direct  loss  of  albumin  from  the  blood,  as  in  bleeding 
albuminuria,  dysentery,  abundant  formation  of  pus,  etc.,  etc.  The 
amount  of  fibrin  is  increased  (hyperinose)  in  inflammatory  dis- 
eases, pneumonia,  acute  muscular  rheumatism,  and  erysipelas,  in 
which  the  blood  yields  a  "crusta  phlogistica"  because  it  coagu- 
lates more  slowly.  The  statements  in  regard  to  the  occurrence  of 
a  hyperinose  in  scurvy  and  hydraemia  seems  to  require  further 
investigation.  A  decrease  in  the  amount  of  fibrin  (hypinose)  has 
been  observed  in  malaria,  pyaemia,  and  malignant  anaemia.  Tliese 
statements  also  require  further  corroboration. 

The  amount  of  fat  in  the  blood  (lip^mia)  increases,  irrespect- 
ive of  the  increase  after  a  diet  rich  in  fat,  in  drunkards,  in  corpu- 
lent individuals,  after  fracture  of  the  bones,  and  also  in  diabetes. 
In  the  last-mentioned  case  the  increase  in  fat  depends,  according 
to  Pavy  and  Hoppb-Seyler,  upon  defective  digestion. 

An  increase  in  the  amount  of  fat  in  the  blood  has  also  been  ob- 
served in  diseases  of  the  liver,  Bright's  disease,  tuberculosis,  mala- 


114  PHYSIOLOGICAL    CHEMISTRY. 

ria,  and  cholera,  v.  Jaksch  has  observed  volatile  fatty  acids  in 
the  blood  (lipacid^mia)  in  febrile  diseases  and  sometimes  in  dia- 
betes. 

The  amount  of  salts  in  the  blood  is  increased  in  dropsy,  dysen- 
tery, and  in  cholera  immediately  after  the  first  violent  attack,  but 
diminishes  later  after  the  attack  in  cholera,  in  scurvy,  and  in 
inflammatory  diseases.  The  decrease  of  alkali  salts,  especially  com- 
mon salt,  is  only  trifling,  but  in  pneumonia  the  salt  disappears 
almost  entirely  from  the  urine.  A  decrease  in  the  alkalinity  of  the 
blood  has  been  observed  in  many  cases,  as  in  fevers,  uraemia,  car- 
bon-monoxide poisoning,  diseases  of  the  liver,  leucaemia,  malignant 
anaemia,  and  diabetes.  The  above-mentioned  (page  104)  decrease 
in  the  alkalinity  of  the  blood  in  diabetes  mellitus  is  of  special  in- 
terest. 

The  quantity  of  glucose  is  increased  in  diabetes  (mellitasmia). 
Hoppe-Setler  found  in  one  case  9  p.  m.  glucose  in  the  blood. 
According  to  Claude  Beenard,  when  the  quantity  of  glucose  in 
the  blood  amounts  to  3  p.  m.  it  passes  into  the  urine.  The 
quantity  of  urea  is  augmented  in  fevers,  also  in  increased  exchange 
of  albumin,  and  by  an  increased  formation  of  urea  caused  thereby. 
A  further  increase  in  the  amount  of  urea  in  the  blood  occurs  in  a 
retarded  micturition,  as  in  cholera  as  well  as  in  cholera  infantum 
(K.  Morner),  and  in  affections  of  the  kidneys  and  the  urinary 
passages.  After  a  ligature  of  the  ureters  or  after  extirpation  of 
the  kidneys  of  animals  an  accumulation  of  urea  takes  place  in  the 
blood.  In  uraemia,  ammonia  may  occur  in  the  blood,  which  origi- 
nates from  a  decomposition  of  the  urea.  Uric  acid  is  found  in- 
creased in  the  blood  in  gout  (Garrod,  Salomon);  oxalic  acid  was 
also  found  in  the  blood  in  the  same  disease  by  Garrod. 

Among  the  foreign  lodies  which  are  found  in  the  blood  the  fol- 
lowing must  be  mentioned  here:  biliary  acids  and  biliary  col- 
oring MATTERS  (which  latter  may  occur  under  physiological  condi- 
tions in  a  few  varieties  of  blood)  in  iceterus;  leucin  and  tyrosin 
in  acute  atrophy  of  the  liver ;  acetok  specially  in  fevers  (v.  Jaksch). 
In  melanaemia,  especially  after  continuous  malarial  fever,  black, 
less  often  light  brown  or  yellowish,  grains  of  pigment  occur  in  the 
blood,  which,  according  to  the  generally-received  opinion,  come  into 
the  blood  from  the  spleen.     After  poisoning  with  potassium  chlo- 


rUE  BLOOD.  115 

rate,  metahaemoglobin  is  observed  in  human  and  in  canine  blood 
(Makchaxd  and  Kahn)  ;  but,  on  the  contrary,  no  formation  of 
metahaemoglobin  takes  place  in  the  blood  of  rabbits  (Stokvis  and 
Kimmyser).  a  formation  of  metahgemoglobiu  may  be  caused  at 
the  expense  of  the  haemoglobin  by  the  inhalation  of  amyl  nitrite, 
as  also  by  the  action  of  a  number  of  other  medicinal  bodies  (Hatem 
and  others). 

The  quantity  of  blood  is  indeed  somewhat  variable  in  different 
species  of  animals  and  in  different  conditions  of  the  body;  in  gen- 
eral we  consider  the  entire  quantity  of  blood  in  adults  as  about 
jIj-yV  of  the  weight  of  the  body,  and  in  new-born  infants  about 
yiy.  Fat  individuals  are  relatively  poorer  in  blood  than  lean  ones. 
During  inanition  the  quantity  of  blood  decreases  less  quickly  than 
the  weight  of  the  body  (Panum),  and  it  may  therefore  be  also  pro- 
portionally greater  in  starving  individuals  than  in  well-fed  ones. 

By  careful  bleeding  the  quantity  of  blood  may  be  considerably 
diminished  without  any  dangerous  symptoms.  The  loss  of  blood 
to  \  of  the  normal  quantity  has  as  sequence  no  durable  sinking  of 
the  blood-pressure  in  the  arteries;  while  the  smaller  arteries  ac- 
commodate themselves  to  the  small  quantities  of  blood  by  contract- 
ing (Worm  Mijller).  A  loss  of  blood  to  \  of  the  quantity  reduces 
the  blood-pressure  considerably,  and  a  loss  of  ^  of  the  blood  in 
adults  is  dangerous  to  life.  The  faster  the  bleeding  the  more  dan- 
gerous it  is.  New-born  infants  are  very  sensitive  to  loss  of  blood, 
and  likewise  fat,  old,  and  weak  persons  cannot  stand  much  loss  of 
blood.     Women  can  stand  loss  of  blood  better  than  men. 

The  quantity  of  blood  may  be  considerably  increased  by  the  in- 
jection of  blood  from  the  same  species  of  animal  (Panum,  Landois, 
WoRii  MiJLLER,  Ponfick).  According  to  Worm  Muller,  the  nor- 
mal quantity  of  blood  may  indeed  be  increased  to  83^  without  pro- 
ducing any  abnormal  conditions  or  continuing  high  blood-pressure. 
An  increase  of  the  quantity  of  blood  to  150'^  may  be  directly  dan- 
gerous to  life  (Worm  Mijller).  If  the  quantity  of  blood  of  an 
animal  is  increased  by  transfusion  with  blood  of  the  same  kind  of 
animal,  an  abundant  formation  of  lymph  takes  place.  The  water  in 
excess  is  eliminated  by  the  urine;  and  as  the  albumin  of  the  blood 
serum  is  quickly  decomposed,  while  the  red  blood-corpuscles  are 


116  PHY810L0OIGAL   CHEMISTRY. 

destroyed  much  more  slowly  (Tschiejew,  Fokstee,  Panum,  Worm: 
MiJLLER),  a  polycythgemia  is  gradually  produced. 

If  blood  of  another  kind  is  transfused,  then  under  certain  con- 
ditions, according  to  the  quantity  of  blood  introduced,  more  or  less 
menacing  symptoms  appear.  These  appear,  for  instance,  when  the 
blood-corpuscles  of  the  receiver  are  dissolved  easily  by  the  serum  of 
the  introduced  blood,  as,  for  example,  the  blood-corpuscles  of  rab- 
bits on  transfusion  with  a  different  kind  of  blood,  or  the  reverse, 
when  the  blood-corpuscles  of  the  transfused  blood  are  dissolved  by 
the  blood  of  the  receiver;  for  instance,  when  the  blood  of  a  dog  is 
transfused  with  rabbit's  or  lamb's  blood,  or  the  blood  of  a  man  with 
lamb's  blood  (Landois).  Before  dissolving,  the  blood-corpuscles 
may  unite  in  tough  agglomerated  heaps,  which  clog  up  the  smaller 
vessels  (Landois).  On  the  other  hand,  the  stromata  of  the  dissolved 
blood-corpuscles  may  also  give  rise  to  an  extensive  intravascular 
coagulation  causing  death. 

The  transfusion  should  therefore  when  possible  be  made  with 
the  blood  of  the  same  kind  of  animal,  and  for  the  resuscitating 
action  of  the  blood  it  is  immaterial  whether  or  not  it  contains  the 
fibrin  or  the  mother-substance  of  the  same.  The  action  of  trans- 
fused blood  depends  on  its  blood-corpuscles,  and  therefore  defibri- 
nated  blood  acts  just  like  non-defibrinated  (Panum,  Lakdois). 

The  quantity  of  blood  in  the  different  organs  depends  essentially 
on  the  activity  of  the  same.  During  work  the  exchange  of  mate- 
rial in  an  organ  is  more  active  than  when  at  rest,  and  the  increased 
exchange  of  material  is  combined  with  a  more  abundant  flow  of 
blood.  Although  the  total  quantity  of  blood  in  the  body  remains 
constant,  the  distribution  of  the  blood  in  the  various  organs  may 
be  different  at  different  times.  As  a  rule,  the  quantity  of  blood  in 
an  organ  can  be  an  approximate  measure  of  the  more  or  less  active 
exchange  of  material  going  on  in  the  same,  and  from  this  point  of 
view  the  distribution  of  the  blood  in  the  different  organs  and  groups 
of  organs  is  of  interest.  According  to  Eanke,  to  whom  we  are 
especially  indebted  for  our  knowledge  of  the  relationship  of  the 
activity  of  the  organs  to  the  quantity  of  blood  contained  therein,  of 
the  total  quantity  of  blood  (in  the  rabbit)  about  ^  comes  to  the 
muscles  in  rest,  \  to  the  heart  and  the  large  blood-vessels,  ^  to  the 
liver,  and  \  to  the  other  organs. 


CHAPTER  V. 
CHYLE,  LYMPH.  TRANSUDATIONS  AND  EXUDATIONS. 

I.  Chyle  and  Lymph. 

Feom  the  close  relationship  which  exists  between  blood  and 
lymph,  and  the  dependence  which  the  formation  of  lymph  has  upon 
the  blood-circnlation  and  the  blood-pressure,  it  is  to  be  expected  that 
a  close  correspondence  in  the  chemical  constitution  between  blood- 
plasma  and  lymph  should  exist.  The  lymph  is  generally  considered 
as  transudated  plasma.  Qualitatively  the  lymph  contains  the  same 
substances  as  the  plasma.  The  essential  difference  is  of  a  quantita- 
tive nature  and  consists  in  that  the  lymph  is  poorer  in  albumin. 
No  essential  chemical  difference  has  been  found  between  the  lymph 
and  the  chyle  of  starving  animals.  After  the  assimilation  of  fatty 
food  the  chyle  differs  from  the  lymph  in  its  wealth  of  minutely- 
divided  fat-globules  which  give  it  a  milky  appearance;  hence  the 
old  name  "  milk-juice." 

Chyle  and  lymph,  as  well  as  the  plasma,  contain  serum  albumin, 
serum  globulin,  fibrinoge?i,  and  fibrin  ferment.  The  two  last-men- 
tioned bodies  occur  only  in  very  small  amounts;  therefore  the 
chyle  and  lymph  coagulate  slowly  (but  spontaneously)  and  yield  but 
little  fibrin.  Like  other  liquids  poor  in  fibrin  ferment,  chyle  and 
lymph  do  not  at  once  coagulate  completely,  but  repeated  coagula- 
tions take  place. 

The  extractive  bodies  seem  to  be  the  same  as  in  plasma.  Glucose 
is  found  in  about  the  same  quantity  as  in  the  blood-serum 
(v.  Meking),  but  in  larger  quantities  than  in  the  blood  (Poisef- 
ILLE  and  Lefort,  Ginsberg);  this  depends  on  the  fact  that  the 
blood-corpuscles  contain  no  glucose.    The  amount  of  urea  has  been 

117 


118  PHYSIOLOGICAL   CHEMISTRY. 

determined  by  Wurtz  as  0.12-0.28  p.  m.    The  mineral  bodies  appear 
to  be  the  same  as  in  plasma. 

As  form -elements  leucocytes  and  red  Mood-corpuscles  are  com- 
mon to  both  chyle  and  lymph.  When  it  has  not  left  the  connivent 
valves  chyle  contains  very  few  leucocytes,  but  in  the  vessels  mov- 
ino-  on  the  peritoneal  side  of  the  intestines  it  is  richer  in  leuco- 
cytes. The  greatest  quantity  of  leucocytes  is  found  in  the  chyle 
between  the  great  mesenteric  gland  and  the  cisterna  chyli.  The 
chyle  is  poorer  in  leucocytes  in  the  thoracic  duct,  probably  because 
a  mixing  takes  place  here  with  lymph,  from  other  parts  of  the  body 
that  is  poorer  in  form-constituents. 

The  red  blood-corpuscles  occur  in  the  chyle  and  lymph  in  very 
small  quantities.  In  these  liquids,  which  seem  to  be  free  from 
oxygen,  the  blood-corpuscles  are  darker-colored,  and  only  after  they 
have  come  in  contact  with  the  air  do  they  have  the  light-red  color 
of  oxyhsemoglobin  and  give  the  surface  of  the  fibrin  clot  a 
beautiful  light-red  appearance.  It  has  been  suggested  that  this  red 
color  originates  from  the  transition  forms  between  red  and  white 
blood-corpuscles,  in  which  blood-coloring  matters  are  first  formed  by 
the  action  of  the  oxygen. 

The  chyle  of  starving  animals  has  the  appearance  of  lymph.  After 
partaking  of  fat  or  food  rich  in  fat  it  is  milky,  and  this  is  partly 
due  to  the  presence  of  large  fat-globules,  as  in  milk,  or  partly,  and 
indeed  chiefly,  the  finely-divided  fat.  The  nature  of  the  fats 
occurring  in  the  chyle  depends  on  the  variety  of  fat  in  the  food. 
The  disproportionally  greater  part  consists  of  neutral  fats,  and  even 
after  feeding  with  abundant  amounts  of  free  fatty  acids  MuiS'K  and 
Lebedbff  found  in  the  chyle  chiefly  neutral  fats  with  a  small 
quantity  of  fatty  acids  or  soaps. 

The  gases  of  the  chyle  have  not  been  studied,  and  it  seems 
that  the  gases  of  an  entirely  normal  human  lymph' have  not  thus  far 
been  investigated.  The  gases  from  dog-lymph  contain  only  traces 
of  oxygen  and  consist  of  37.4-53.1^  CO,  and  l.Qfo  N  (author)  calcu- 
lated at  0°  0.  and  760  mm.  mercury.  The  chief  mass  of  the  carbon 
dioxide  of  the  lymph  seems  to  be  firmly  chemically  combined. 
Comparative  analyses  of  blood  and  lymph  have  shown  that  the 
lymph  contains  more  carbon  dioxide  than  arterial  but  less  than 
venous  blood.      The  tension  of  the  carbon  dioxide  of  lymph  is, 


CHYLE,  L  YMPH,  TRANS  UDA  TIONS  AND  EX  UDA  TI0N8.     119 

according  to  Pfluger  and  Strassburg,  smaller  than  in  venous  but 
greater  than  in  arterial  blood. 

The  qnantitative  constitution  of  the  chyle  must  naturally  be  very 
variable.  The  analyses  thus  far  made  refer  only  to  that  mixture  of 
chyle  and  lymph  which  is  obtained  from  the  thoracic  duct.  The 
specific  gravity  varies  between  1.007  and  1.043.  As  example  of 
the  constitution  of  human  chyle  we  will  here  give  two  analyses. 
The  first  is  by  Owejst-Eees,  of  the  chyle  of  an  executed  person,  and 
the  second  by  Hoppe-Seyler,  of  the  chyle  in  a  case  of  rupture  of 
the  thoracic  duct.  In  the  latter  case  the  fibrin  had  previously 
separated.     The  results  are  in  1000  parts. 

No.  1.        No.  2. 

Water 904.8         940.72  water 

Solids 95.1  59.28  solids 

Fibrin traces 

Albumin 70.8  36.67  albumin 

Fat 9.2  7.23  fat 

2.35  soaps 
ro.88  lecithin 
-n        •   •  •    1     )•  mo  1.32  cbolesterin 

Remaming  organic  bodies      10.8  g^g.^  ^,^^,,^i  extractives 


Salts 4.4 


1^0  57  water  extractives 
j  ti.8i>  soluble  salts 
[  0.35  insoluble  salts 


The  quantity  of  fat  is  very  variable  and  may  be  considerably  in- 
creased by  partaking  food  rich  in  fats. 

A  great  many  analyses  of  chyle  from  animals  have  been, 
made,  and  they  chiefly  show  the  fact  that  the  chyle  is  a  liquid  with 
a  very  changeable  composition  which  stands  closely  related  to  blood- 
plasma,  but  with  the  chief  difference  that  it  contains  more  fat  and 
less  solids.  The  reader  is  referred  to  special  works  for  these 
analyses,  as,  for  example,  to  v.  Gorup-Besanez's  "  Lehrbuch  der 
physiologischen  Chemie,"  4th  edition. 

The  composition  of  the  lymph  is  also  very  changeable,  and  its 
specific  gravity  shows  about  the  same  variation  as  the  chyle.  In 
the  following  analyses,  1  and  2,  made  by  Gubler  and  Quevestne, 
are  the  results  obtained  from  lymph  from  the  upper  part  of  the 
thigh  of  a  woman  aged  39;  and  3,  made  by  v.  Scherer,  is  an  analysis 
of  lymph  from  the  sac-like  dilated  vessels  of  the  spermatic  cord.  No. 


3 

3 

4 

)34.8 

957.6 

955.4 

65.2 

43.4 

44.6 

0.6 

0.4 

3.2 

43.8 

34.7) 

9.3 

....t 

34.9 

4.4 

....) 

8.3 

7.3 

7.5 

120  PHYSIOLOGICAL   CHEMISTRY. 

4  was  made  by  C.  Schmidt,  the  data  being  obtained  from  lympli 
from  the  neck  of  a  colt.     The  results  are  in  parts  per  1000. 

1 

Water 939.9 

Solids 60.1 

Fibrin 0.5 

Albumin 43.7 

Fat,  cbolesterin,  lecithin      3.8 
Extractive   bodies. .....      5.7 

Salts 7.3 

The  mixture  of  salts  found  by  C.  Schmidt  in  the  lymph  of  the 
horse  has  the  following  composition,  calculated  in  parts  per  1000 
parts  of  the  lymph : 

Sodium  chloride 5.67 

Soda 1.37 

Potash 0.16 

Sulphuric  acid 0.09 

Phosporic  acid  united  with  alkalies 0.02 

Earthy  phosphates 0.36 

Under  pathological  conditions  the  lymph  may  be  so  rich  in 
finely-divided  fat  that  it  appears  like  chyle.  Such  lymph  has  been 
investigated  by  Hensen  in  a  case  of  lymph  fistula  in  a  ten-year-old 
boy,  and  by  Lang  in  a  case  of  lymph  fistula  in  the  left  upper  part 
of  the  thigh  of  a  girl  of  seventeen.  The  lymph  investigated  by 
Hensen"  contained  as  an  average  of  nineteen  analyses  19  p.  m.  of 
fat  and  0.6  p.  m.  of  cholesterin,  while  that  investigated  by  LA]srG 
contained  24.8  p.  m.  of  fat. 

The  quantity  of  chyle  and  lymph  must  naturally  change  con- 
siderably, therefore,  for  this  and  other  reasons,  the  calculations  of 
the  quantity  in  24  hours  are  not  to  be  depended  upon.  The  food 
plays  a  very  important  role  in  the  quantity  of  chyle  and  lymph. 
Nasse  has  observed  in  dogs  that  the  formation  of  lymph  is  36^ 
more  after  feeding  with  meat  than  after  feeding  with  potatoes,  and 
about  54^  more  than  after  24  hours'  deprivation  of  food. 

The  amount  of  lymph  is  increased  by  the  following  influences, 
namely,  by  increasing  the  total  quantity  of  blood,  as  by  transfusion 
of  blood  (WoKM  Muller),  raising  the  blood-pressure  (Ludwig  and 
Tomsa),  increased  influx  of  the  arterial  blood  (LuDwiG,  Eagowicz, 
GiANUZZi),  and,  above  all,  by  preventing  the  discharge  of  the  blood 


CHYLE,  LYMPH,  TRANSUDATIONS  AND  EXUDATIONS     121 

by  tying  the  veins  (Bidder,  Emminghaus,  Weiss).  The  quantity 
of  lymph  is  also  increased  by  strong  active  or  passive  muscular 
movements  (Lesser).  On  poisoning  with  curara  the  secretion  of 
lymph  is  increased  (Puschutin,  Lesser),  and  the  solids  of  the 
lymph  are  also  increased  at  the  same  time. 


II.  Transudations  and  Exudations. 

The  serous  membranes  are  normally  kept  moistened  by  liquids 
whose  quantity  is  only  sufficient  in  a  few  instances,  as  in  the 
pericardial  cavity  and  the  arachnoid  membrane,  for  a  complete 
chemical  analysis  to  be  made  of  them.  Under  diseased  conditions 
an  abundant  transudation  may  take  place  from  the  blood  into  the 
serous  cavities,  into  the  subcutaneous  tissues,  or  under  the  epi- 
dermis; and  in  this  way  pathological  transudations  are  formed. 
Such  true  transudations,  which  are  similar  to  lymph,  are  generally 
poor  in  form-elements  and  leucocytes,  and  yield  only  very  little  or 
almost  no  fibrin,  while  the  inflammatory  transudations,  the  so-called 
exudations,  are  generally  rich  in  leucocytes  and  yield  proportionally 
more  fibrin.  As  a  rule,  the  richer  a  transudation  is  in  leucocytes 
the  closer  it  stands  to  pus,  while  when  it  has  a  diminished  quantity 
of  leucocytes  it  is  more  nearly  like  real  transudations  or  lymph. 

It  is  ordinarily  accepted  that  filtration  is  of  the  greatest  im- 
portance in  the  formation  of  transudations  and  exudations.  The 
facts  coincide  with  this  view,  namely,  that  all  these  fluids  contain 
the  salts  and  extractive  bodies  occurring  in  the  blood-plasma  in 
about  the  same  quautity  as  the  blood -plasma,  while  the  amount  of 
albumin  is  habitually  smaller.  While  the  dift'erent  fluids  belong- 
ing to  this  group  have  about  the  same  quantities  of  salts  and 
extractive  bodies,  they  differ  from  each  other  chiefly  in  containing 
differing  quantities  of  albumin  and  form-elements,  as  well  as 
varying  quantities  of  transformation  and  decomposition  products 
of  these  latter — changed  blood-coloring  matters,  cholesterin,  etc., 
etc.  The  largest  quantity  of  albumin  habitually  occurs  in  in- 
flammatory processes  with  changed  permeability  of  the  walls  of 
the  vessels.  The  condition  of  the  capillaries  in  the  different 
vascular  regions  affects  the  amount  of  albumin.     For  example,  the 


122  PHYSIOLOGICAL   CHEMISTRY. 

amount  of  albumin  in  the  pericaedial,  pleural,  and  PEEiTOisrEAL 
FLUIDS  is  considerably  greater  than  in  those  fluids  which  are  found 
in  the  arachnoid  membrane,  in  the  sub-cutaneous  tissues,  or  in 
the  aqueous  humor.  The  condition  of  the  blood  also  greatly 
affects  the  transudations,  for  in  hydraemia  the  amount  of  albumin 
in  the  transudation  is  very  small.  With  the  increase  of  the  age  of 
a  transudation,  of  a  hydrocele  fluid  for  instance,  the  quantity  of 
albumin  is  increased,  probably  by  resorption  of  water,  and  indeed 
exceptional  cases  may  occur  in  which  the  amount  of  albumin,  with- 
out any  previous  bleeding,  is  greater  than  in  the  blood-serum. 
It  is  natural  to  suppose  that  the  state  of  the  circulation  and  the 
pressure  must  have  an  influence  on  the  quantity  and  composition 
of  the  transudation  even  though  their  action  is  little  known.  By 
increasing  the  vein-pressure  Senator  caused  an  increase  in  the 
quantity  of  transudation  and  the  amount  of  albumin  contained 
therein,  while  the  amount  of  salts  was  not  essentially  changed.  Of 
the  variation  in  the  amount  of  albumin  by  simple  arterial  hypersemia 
nothing  is  positively  known. 

The  gases  of  the  transudations  consist  of  carbon  dioxide  besides 
small  amounts  of  nitrogen  and  traces  of  oxygen.  The  tension  of 
the  carbon  dioxide  is  greater  in  the  transudations  than  in  the  blood 
(Ewald).  On  mixing  with  pus  the  amount  of  carbon  dioxide  is 
decreased. 

The  extractives  are,  as  above  stated,  the  same  as  in  the  blood- 
plasma;  but  sometimes  extractive  bodies  occur,  such  as  allantoin 
in  dropsical  fluids  (Moscatelli),  which  have  not  been  detected  in 
the  blood.  Urea  seems  to  occur  in  very  variable  amounts.  Glucose, 
or  at  least  a  substance  which  reduces  copper  oxide  in  alkaline 
liquids,  occurs  in  most  transudations.  Succinic  acid  has  been 
found  in  a  few  cases  in  hydrocele  fluids,  while  in  other  cases  it  is 
entirely  absent.  Leucin  and  tyrosin  have  been  found  in  transuda- 
tions from  diseased  livers  and  in  pus-like  transudations  which  have 
decomposed.  Among  other  extractives  found  in  transudations  we 
must  mention  uric  acid,  allantoin,  xanthin,  creatin,  iiiosit,  and 
pyrocatecliin. 

As  above  stated,  irrespective  of  the  varying  number  of  form- 
elements  contained  in  the  dift'erent  transudations,  the  quantity  of 
albumin  is  the  most  characteristic  chemical  distinction  in  their 


CHYLE,  LYMPH,   TRANSUDATIONS  AND  EXUDATIONS.     123 

compositiou;  therefore  a  quantitative  analysis  is  of  little  impor- 
tance except  in  determining  the  quantity  of  albumin. 

Pericardial  Fluid.  The  quantity  of  this  fluid  is  also,  under 
certain  physiological  conditions,  so  large  that  a  suflficient  quantity 
for  chemical  investigation  was  obtained  from  a  person  who  had  been 
executed.  This  fluid  is  lemon-yellow  in  color,  somewhat  sticky, 
and  yields  more  fibrin  than  other  transudations  (6-8  p.  m.).  The 
amount  of  solids,  according  to  the  analyses  performed  by  v.  Gorup- 
Besanez,  Wachsmuth,  and  Hoppe-Seyler,  is  37.5-44.9  p.  m.,and 
the  amount  of  albumin  is  22.8-24.7  p.  m.  In  a  case  of  chyloperi- 
cardium,  which  was  probably  due  to  the  rupture  of  a  chylus  vessel 
or  caused  by  a  capillary  exudation  of  chyle  because  of  stowing, 
Hasebroek  found  in  1000  parts  of  the  analyzed  fluid  103.61  parts 
solids,  73.79  albuminous  bodies,  10.77  fat,  3.34  cholesterin,  1.77 
lecithin,  and  9.34  salts. 

The  pleural  fluid  occurs  under  physiological  conditions  in  such 
small  quantities  that  a  chemical  analysis  of  the  same  cannot  be 
made.  Under  pathological  conditions  this  fluid  may  show  very 
variable  properties.  In  a  few  cases  it  is  nearly  serous,  in  others 
again  sero-fibrinous,  and  in  others  similar  to  pus.  There  is  a 
corresponding  variation  in  the  specific  gravity  and  the  properties  in 
general.  If  a  pus-like  exudation  is  kept  closed  for  a  long  time  in 
the  pleural  cavity,  a  more  or  less  complete  maceration  and  solution 
of  the  pus-corpuscles  is  found  to  take  place.  The  ejected  yellowish- 
brown  or  greenish  fluid  may  then  be  as  rich  in  solids  as  the  blood- 
serum;  and  an  abundant  flocculent  precipitate  of  a  neucleo-albumin 
(the  pyin  of  early  writers)  may  be  obtained  on  the  addition  of 
acetic  acid.  This  precipitate  is  soluble  with  difficulty  by  adding  an 
excess  of  acetic  acid. 

According  to  Mehu,  who  has  investigated  a  great  number  of 
pleural  fluids,  the  specific  gravity  is  generally  higher  than  1.020  in 
acute  pleurisy,  the  amount  of  solids  is  6.5  p.  m.,  and  the  quantity 
of  fibrin  not  higher  than  1.2  p.  m.  In  chronic  pleurisy  with  gath- 
ering of  pus  the  specific  gravity  is  higher  than  1.018  and  may  rise  to 
1.024  (according  to  the  observations  of  the  author  it  may  rise  indeed 
to  1.030).  The  quantity  of  solids  may  in  these  cases  be  60-70  p.  m. 
or  even  more — 90-100  p.  m.  (author).  Fibrin  is  absent.  In  dis- 
turbed circulation,  as  in  cirrhosis  of  the  liver  or  in  heart  troubles, 


124  PHYSIOLOGICAL   CHEMISTRY. 

the  specific  gravity  is  usually  lower  than  1.015  and  the  quantity  of 
solids  averages  20-30  p.  m. 

The  quantity  of  peritoneal  fluid  is  very  small  under  physiologi- 
cal conditions.  The  investigations  refer  only  to  the  fluid  under 
diseased  conditions  {dropsical  or  ascites  fluid.)  The  color,  trans- 
parency, and  consistency  of  these  may  vary  greatly. 

In  cachectic  conditions  the  fluid  is  nearly  colorless,  milky-opal- 
escent, watery,  does  not  coagulate  spontaneously,  is  of  a  very  low 
specific  gravity,  1.005-1.015,  and  nearly  free  from  form-constituents. 
In  carcinomatous  peritonitis  it  may  have  a  cloudy,  dirty-gi-ay  appear- 
ance due  to  its  richness  in  form-elements  of  various  kinds.  The 
specific  gravity  is  then  higher,  the  quantity  of  solids  greater,  and  it 
often  coagulates  spontaneously.  In  inflammatory  processes  it  is 
straw-  or  lemon-yellow  in  color,  somewhat  cloudy  or  reddish,  due  to 
leucocytes  and  red  blood-corpuscles,  and  from  great  richness  in  leu- 
cocytes it  may  appear  more  like  pus.  It  coagulates  spontaneously, 
may  be  relatively  richer  in  solids,  and  may  have  a  specific  gravity 
of  1.030  or  more.  By  rupture  of  a  chylous  vessel  the  dropsical 
fluid  may  be  rich  in  very  flnely-emulsified  fat  (chylous  ascites). 
In  such  cases  3.86-10.30  p.  m.  fat  has  been  found  in  the  dropsical 
fluid  (GrUiNOCHET,  Hat).  By  admixture  of  this  fluid  with  the 
fluid  from  an  ovarian  cyst  it  may  sometimes  contain  pseudomucin 
(see  Chapter  XI).  We  also  have  cases  in  which  the  ascitical  fluid 
contains  mucoids  which  may  be  precipitated  by  alcohol  after 
removal  of  the  albumins  by  coagulation  at  boiling  temperature. 
Such  substances,  which  yield  a  reducible  substance  on  boiling  with 
acids,  have  been  found  by  the  author  in  tuberculous  peritonitis  and 
in  cirrhosis  hepatis  syphilitica. 

In  order  to  show  the  amount  of  albumin  in  ascitic  fluids  we 
give  below  the  results  of  Runeberg's  analyses.  They  are  in  parts 
per  1000  parts  of  the  fluid. 

Max.        Mia.    Average. 

Ascitic  fluid  in.  hydrsemia 4.1  0.2  2.1 

"         "      "  portal  obstruction 26.8  3.7  9.7 

"  "     "  heart  disease 23.0  8.4  16.7 

'*         "     "  carcinomatous  peritonitis.  54.2         27.0         35.1 

Urea  has  also  been  found  in  ascitical  fluids,  sometimes  only  as  traces,  some- 
times in  larger  quantities  (4  p.  m.  in  albuminuria),  also  uric  acid,  allantoin  in 
cirrhosis  of  the  liver  (Moscatelli),  xanthin,  creatin,  cholesterin,  and  glucose. 


CHYLE,  LVMl'JI,  THAN8UDATI0N8  AND  EXUDATIONS.     125 

Hydrocele  and  Spermatocele  Fluids.  These  fluids  differ  from 
each  other  in  various  ways.  The  hydrocele  fluids  are  generally 
colored  light  or  darker  yellow,  sometimes  brownish  with  a  shade  of 
green.  They  have  a  relatively  higher  specific  gravity,  1.016-1.026, 
with  a  variable  but  generally  higher  amount  of  solids,  an  average  of 
60  p.  m.  They  sometimes  coagulate  spontaneously,  sometimes  only 
after  the  addition  of  fibrin  ferment  or  blood.  They  contain  as 
form-elements  chiefly  leucocytes.  Sometimes  they  contain  smaller 
or  larger  amounts  of  cholesferin  crystals. 

The  spermatocele  fluids,  on  the.  contrary,  are  as  a  rule  colorless, 
thin,  cloudy  like  water  mixed  with  milk.  They  sometimes  have  an 
acid  reaction.  They  have  a  lower  specific  gravity,  1.006  to  1.010,  a 
lower  amount  of  solids — an  average  of  about  13  p.  m., — and  do  not 
coagulate  either  spontaneously  or  after  the  addition  of  blood.  They 
are,  as  a  rule,  poor  in  albumin  and  contain  spermatozoa,  cell-detri- 
tus,  and  fat-glohules  as  form -constituents.  To  show  the  unequal 
composition  of  these  two  kinds  of  fluids  we  will  give  the  average 
results  (calculated  in  parts  per  1000  j)arts  of  the  fluid)  of  17  analy- 
ses of  hydrocele  fluids  and  4  of  spermatocele  fluids  made  by  the 
author : 

Hydrocele.      Spermatocele. 

Water 938.35  986.33 

Solids 61.15  18.17 

Fibrin  0.59  

Globulin 13.52  0.59 

Serum  albumin 35.94  1.82 

Ether  extractive  bodies 4.02  ) 

Soluble  salts 8.60^  10.76 

Insoluble  salts 0.66  ) 

In  the  hydrocele  fluids  traces  of  urea  and  a  reducing  subsiance  have  been 
found,  and  in  a  few  cases  also  succinic  acid  and  inosit. 

Cerebrospinal  Fluid.  This  fluid,  which  in  certain  respects  is 
more  of  a  secretion  than  a  transudation  (C.  Schmidt,  Hallibue- 
Tox),  is  thin,  water-clear,  and  has  a  low  specific  gravity  (1.005). 
It  is  very  poor  in  solids,  10-15  p.  m.,  and  ordinarily  contains  about 
10  p.  m.  albumin.  This  albumin  is  generally  a  mixture  of  glohu- 
lin  and  alhumose  /  occasionally  some  peptone  occurs,  and  more 
rarely,  in  special  cases,  serum  albumin  appears  (Halliburton). 
An  optically  inactive,  non-fermentable,  reducible  substance,  seem- 
ingly pyrocatechin  (Halliburtox),  has  been  observed  in  this  fluid. 


126  PHYSIOLOGICAL   CHEMISTRY. 

The  older  statement  that  the  cerebro-spinal  fluid  differs  from  the 
transudations  in  a  greater  wealth  of  potassium  salts  has  not  been 
confirmed  by  recent  investigations. 

Aqueous  Humor,  This  fluid  is  clear,  alkaline,  and  has  a  sjoecific 
gravity  of  1.003-1.009.  The  amount  of  solids  is  on  an  average  13 
p.  m.  and  the  amount  of  proteids  only  0.8-1.2  p.  m.  The  proteids 
consists  of  about  equal  parts  serum  globulin  and  gloMilin  (Kahk), 
According  to  GtRUENHAGE^st,  it  contains  paralactic  acid,  another 
dextro-gyrate  substance,  and  a  reducible  body  which  is  not  similar 
to  glucose  or  dextrine. 

Blister-fluid.  The  content  of  blisters  caused  by  burns,  and  of 
vesicator  blisters  and  the  blisters  of  the  pem.phigus  clironicus,  is 
generally  a  fluid  rich  in  solids  and  albumin  (40-65  p.  m.).  This 
is  especially  true  of  the  contents  of  vesicatory  blisters,  which  also 
contain  a  substance  that  reduces  copper  oxide.  The  fluid  of  the 
pemphigus  is  slimy  and  alkaline  in  reaction. 

The  fluid  of  subcutaneous  oedema.  This  is,  as  a  rule,  very  poor 
in  solids,  purely  serous,  does  not  contain  fibrinogen,  and  has  a  spe- 
cific gravity  of  1.005  to  1.010.  The  quantity  of  proteids  is  in  most 
cases  lower  than  10  p.m., — according  toHoFFMAN]sr  1-8  p.m., — and 
in  serious  affections  of  the  kidneys,  generally  with  amyloid  degen- 
eration, less  than  1  p.  m.  has  been  shown  (HoFEMA]sr]sr).  The 
oedema  fluid  also  habitually  contains  urea,  1-2  p.  m.,  and  also  a 
reducible  substance. 

The  FLUID  OF  THE  TAPEWORM  cyst  is  related  to  the  transudations.  It  is 
poor  iu  proteids,  thin  and  colorless,  and  has  a  specific  gravity  of  1.005- 
1.015.  The  quantity  of  solids  is  14-30  p.  m.  The  chemical  constituents  are 
glucose  (2.5  p.  m.),  inosit,  traces  of  urea,  creatin,  succinic  acid,  and  salts  (8.3- 
9.7  p.  m.).  Albumin  is  only  found  in  traces,  and  then  only  after  an  inflam- 
matory irritation.  In  the  last-mentioned  case  7  p.  m.  albumin  has  been  found 
in  the  fluid. 

The  Synovial  Fluid  and  Fluid  in  Synovial  Cavities  around  Joints, 
etc.  The  synovia  is  hardly  a  transudation,  but  it  is  often  treated 
as  an  appendix  to  the  transudations. 

The  synovia  is  an  alkaline,  sticky,  fibrous,  yellowish  fluid 
which  is  cloudy,  from  the  presence  of  cell-nuclei  and  remains  of 
destroyed  cells,  but  is  sometimes  clear.  It  contains  also,  besides 
nlbtimin  and  salts,  a  mucin-liJce  nucleoalbumin.  The  presence  of 
pure  mucin  has  not  been  shown.     The  composition  of  synovia  is 


CHYLE,  LYMPH,   TRANSUDATIONS  AND  EXUDATIONS.     127 

not  constant,  but  varies  in  rest  and  in  motion.  In  the  last- 
mentioned  case  the  quantity  of  fluid  is  less,  but  the  amount  of  the 
mucin-like  body,  albumin,  and  of  the  extractive  bodies  is  greater, 
while  the  quantity  of  salts  is  diminished.  This  may  be  seen  from 
the  following  analyses  by  Fkerichs.  The  figures  represent  parts 
per  1000. 

I.  Synovia  from    II.  Synovia  from 
a  Stall-fed  Ox.        a  Field-fed  Ox. 

Water 969.9  948.5 

Solids i30.1  51.5 

Mucin-like  body 2.4  5.6 

Albumin  and  extractives 15.7  35.1 

Fat 0.6  0.7 

Salts 11.3  9.9 

The  synovia  of  new-born  babes  corresponds  to  that  of  resting 
animals.  The  fluid  of  the  brusae  mucosae,  as  also  the  fluid  in  the 
synovial  cavities  around  joints,  etc.,  is  similar  to  synovia  from  a 
qualitative  standpoint. 

III.  The  Pus. 

Pus  is  a  yellowish-gray  or  yellowish-green,  creamy  mass  of  a 
faint  odor  and  an  unsavory,  sweetish  taste.  It  consists  of  a  fluid, 
the  pus-serum,  in  which  solid  particles,  the  pus-cells,  swim.  The 
number  of  these  cells  varies  so  considerably  that  the  pus  may  at 
one  time  be  thin  and  at  another  time  so  thick  that  it  scarcely  con- 
tains a  drop  of  serum.  The  specific  gravity,  therefore,  may  also 
greatly  vary,  namely,  between  1.020  and  1.040,  but  ordinarily  it  is 
1.031-1.033.  The  reaction  of  fresh  pus  is  generally  alkaline,  but  it 
may  become  neutral  or  acid  from  a  decomposition  in  which  fatty 
acids,  glycero-phosphoric  acid,  and  also  lactic  acid  are  formed. 
It  may  become  strongly  alkaline  when  putrefaction  occurs  with 
the  formation  of  ammonia. 

In  the  chemical  investigation  of  pus  the  pus-serum  and  the 
pus-corpuscles  must  be  studied  separately. 

Pus-serum.  Pus  does  not  coagulate  spontaneously  nor  after 
the  addition  of  defibrinated  blood.  The  fluid  in  which  the 
pus-corpuscles  are  suspended  is  not  to  be  compared  with  the 
plasma,  but  rather  with  the  serum.  The  pus-serum  is  pale  yellow, 
yellowish  green,  or  brownish  yellow,  and  has  an  alkaline  reaction. 
It  contains,  for  the  most  part,  the  same  constituents  as  the  blood- 


128  PHYSIOLOGICAL   CHEMISTRY. 

serum;  but  sometimes  besides  these — when,  for  instance,  the  pus 
has  remained  in  the  body  for  a  long  time, — it  contains  a  nucleo- 
albumin  which  is  precipitated  by  acetic  acid  and  soluble  with  great 
difficulty  in  an  excess  of  the  acid  {pyin  of  the  older  authors). 
This  nucleoalbumin  seems  to  be  formed  from  the  hyaline  substance 
of  the  pus-cells  by  maceration.  The  pus-serum  contains,  moreover, 
at  least  in  many  cases,  no  fibrin  ferment.  According  to  the  analy- 
ses of  Hoppe-Seylee,  the  pus-serum  contains  in  1000  parts: 

I.  II. 

Water 913.7  905.65 

Solids 86.3  94.35 

Albuminous  bodies 63  23  77.31 

Lecithin 1.50  0  56 

Fat 0.26  0.29 

Cholesterin 0.53  0.87 

Alcohol  extractives 1.52  0.73 

Water  extractives 11.53  6.93 

Inorganic  salts 7.73  7.77 

The  ash  of  pus-serum  has  the  following  composition,  calculated  to  1000 
parts  of  the  serum  : 

I.  II. 

NaCl 3.33  5.39 

Na^SO, 0.40  0.31 

Na^HPO* 0.98  0.46 

NaoCOs 0.49  1.13 

Ca3(P04)2 : 0.49  0.31 

Mg3(P04). 0.19  0.12 

PO4  (in  excess) .05 

The  pus-corpuscles  are  generally  thought  to  consist  in  great 
part  of  emigrated  colorless  blood-corpuscles  (emigration  hypothesis), 
and  their  chemical  properties  have  therefore  been  given  above.  We 
consider  the  molecular  grains,  fat-globules,  and  red  blood-corpuscles 
rather  as  casual  form-elements. 

The  pus-cells  may  be  separated  from  the  serum  by  centrifugal 
force  or  by  decantation  directly  or  after  dilution  with  a  solution  of 
sodium  sulphate  in  water  (1  vol.  saturated  sodium-sulphate  solution 
and  9  vols,  water),  and  then  washed  by  this  same  solution  in  the 
same  manner  as  the  blood-corpuscles. 

The  chief  constituents  of  the  pus-corpuscles  are  albuminous 
bodies  of  which  the  largest  proportion  seems  to  be  a  nucleoalbumi- 
ous  substance  which  is  insoluble  in  water  and  which  expands  into  a 
tough,  slimy  mass  when  treated  with  a  10^  common-salt  solution. 
This  protein  substance,  which    is  soluble  in  alkali    but  quickly 


CHYLE,  LYMPH,  TRANSUDATIONS  AND  EXUDATIONS.     129 

changed  thereby,  is  called  Kovidas's  hyaU7ie  suhstance,  and  the 
property  of  the  pus  of  being  converted  into  a  slime-like  mass  by  a 
solution  of  common  salt  depends  on  this  substance.  Besides  this 
substance  we  find  in  the  pus-cells  also  an  albuminous  body  which 
coagulates  at  48-49°  C,  as  well  as  serum-globulin  (?),  serum- 
albumin,  a  substance  similar  to  coagulated  albumin  (Miescher), 
and  lastly  peptone  (Hofmeister). 

We  also  find  in  the  protoplasm  of  the  pus-cells,  besides  the 
proteids,  lecithin,  cholesterin,  xanthin  bodies,  fat,  soaps,  and 
cerebrin  (see  Chapter  X).  Hoppe-Seyler  claims  that  glycogen 
appears  only  in  the  living,  contractile  white  blood-cells  and  not  in 
the  dead  pus-corpuscles.  Salomok  has  nevertheless  found  glycogen 
in  pus.     The  cell-nucleus  contains  nuclein  and  some  lecithin. 

The  mineral  constituents  of  the  pus-corpuscles  are  potassium, 
sodium,  calcium,  magnesium,  and  iron.  A  part  of  the  alkalies  is 
found  as  chlorides,  and  the  remainder,  as  well  as  the  other  bases,  ex- 
ists as  phosphates. 

The  quantitative  composition  of  the  pus-cells  from  the  analyses 
of  Hoppe-Seyler  is  as  follows,  in  parts  per  1000  of  the  dried 

substance : 

I.  II. 

Albuminous  bodies 137.62  ) 

Nuclein 343.57  [685.85       673.69 

Insoluble  bodies 205. 66  ) 

Lecithin }   j^g  go  75  64 


Fiit f  """•""  75.00 

Cholesterin 74.00  72.83 

Cerebri   51.99 

Extractive  bodies 44.33 


[ 


■'01.84 


MINERAL   SUBSTANCES. 

NaCl 4  35 

Ca3(P04)2 2  05 

Mg3(P04)s 1.13 

FePOi 1.06 

PO4 9.16 

Na 0  68 

K traces  (?) 

Miescher  has  obtained  other  results  for  the  alkali  combinations,  name- 
ly :  potassium  phosphate  12,  sodium  phosphate  6.1.  esirtliy  phosphate  and  iron 
phosphate  4.2,  sodium  chloride  1.4,  and  phosphoric  acid  combined  with 
organic  sub.stances  3.14-2.03  p.  m. 

In  pus  from  congested  abscesses  which  have  stagnated  for  some 
time   we  find  peptone,  leucin  and  tyrosin,  free  fatty  acids   and 


130  PHTSIOLOOICAL   CHEMISTRY. 

volatile  fatty  acids,  sucli  as  formic  acid,  butyric  acid,  valerianic  acid. 
We  also  sometimes  find  cTiondrin  (?)  and  glutin  (?),  ui'ea,  glucose 
(in  diabetes),  Mliary  coloring  matters,  and  Mle  acids  (in  catarrhal 
icterus). 

As  more  specific  but  not  constant  constituents  of  tbe  pus  we 
must  mention  the  following  :  pyin,  which  seems  to  be  a  nucleo- 
albumin  precipitable  by  acetic  acid,  and  also  pyinic  acid  and  chlor- 
rJiodinic  acid,  which  have  been  so  little  studied  that  they  cannot  be 
more  fully  treated  here. 

In  many  cases  a  blue,  more  rarely  a  green  color,  has  been  observed 
in  the  pus.  This  depends  on  the  presence  of  a  variety  of  vibrios 
(LiicKE)  from  which  Fordos  and  LiJCKE  have  isolated  a  crystalliz- 
able  coloring  matter  partly  blue  and  partly  yellow,  pyocyanin  and 
jpyoxanthose. 

Appendix. 

Lymphatic  Glands,  Spleen,  etc. 

The  Lymphatic  Glands.  According  to  Foster  and  Lankester 
and  Halliburton,  we  find  in  the  cells  of  the  lymphatic  glands  the 
four  albuminous  bodies  previously  mentioned  (Chapter  III,  page  42). 
Albumoses  and  peptones  may  also  occur  as  products  of  a  post-mortem 
decomposition.  Besides  the  other  ordinary  tissue-constituents, 
such  as  collagen,  elastin,  and  nuclein,  we  find  in  the  lymphatic 
glands  also  cholesterin,  fat,  glycogen,  xantJiin  bodies  and  adenin 
(Kronecker),  and  leucin.  In  the  inguinal  glands  of  an  old 
woman  Oidtmai^k  found  713.84  p.  m.  water,  285  p.  m.  organic  and 
1.16  p.  m.  inorganic  substances. 

The  Spleen.  The  pulp  of  the  spleen  cannot  be  freed  from 
blood.  The  mass  which  is  separated  from  the  spleen  capsule  and 
the  stnictural  tissue  by  pressure  and  which  ordinarily  serves  as 
material  for  chemical  investigations  is  therefore  a  mixture  of  blood 
and  spleen  constituents.  For  this  reason  the  albuminous  bodies  of 
the  spleen  are  little  known.  As  characteristic  constituents  we  have 
albuminates  containing  iron  and  especially  a  protein  substance 
which  does  not  coagulate  on  boiling  and  which  is  precipitated  by 
acetic  acid  and  yields  an  ash  containing  much  phosphoric  acid  and 
iron  oxide  (Scherer). 


CHYLE,  LYMPH,   TRANSUDATIONS  AND  EXUDATIONS.     131 

The  pulp  of  the  spleen,  when  fresh,  has  an  alkaline  reaction 
but  quickly  turns  acid,  due  partly  to  the  formation  of  free  paralac- 
tic  acid  and  partly  perhaps  to  glycero-phosphoric  acid.  Besides 
these  two  acids  there  have  been  found  in  the  spleen  also  volatile 
fatty  acids,  as  formic,  acetic,  and  butyric  acids,  as  well  as  succinic 
acid,  neutral  fats,  cholesterin,  traces  of  leucin,  inosit  (in  ox-spleen), 
scyllit,  a  body  related  to  inosit  (in  the  spleen  of  plagiostoma), 
glycogen  (in  dog-spleen),  U7'ic  acid,  guanin,  hypoxanthin,  xanthin, 
adenin  (Kroeecker),  Siud  jecorin  (Baldi). 

Among  the  constituents  of  the  spleen  the  deposit  rich  in  iron, 
which  consists  of  ferruginous  granules  or  conglomerate  masses  of 
them,  and  closely  studied  by  Nasse,  is  of  special  interest.  These 
iron  grains  developed  by  the  changing  of  the  red  corpuscles,  and 
which  also  occur  in  old  thrombi,  are  chiefly  produced  when  stag- 
nant blood-corpuscles  are  not  dissolved,  and  they  may  be  formed 
either  extra-cellular  or  intracellular  when  the  blood-corpuscles  of 
the  colorless  cells  are  taken  up.  This  deposit  does  not  occur  to  the 
same  extent  in  the  spleen  of  all  animals.  It  is  found  especially 
abundant  in  the  spleen  of  the  horse.  Nasse  on  analyzing  the  grains 
(from  the  spleen  of  a  horse)  obtained  839.2  p.  m.  organic  and  160.8 
p.  m.  inorganic  substances.  These  last  consisted  of  566-726  p.  m. 
Fe^Og,  205-388  p.  m.  P^O^,  and  57  p.  m.  earths.  The  organic  sub- 
stances consisted  chiefly  of  proteids  (660-800  p.  m.),  nuclein,  52 
p.  m.  (maximum),  a  yellow  coloring  matter,  extractive  bodies,  fat, 
cholesterin,  and  lecithin. 

In  regard  to  the  mineral  constittietits  it  is  to  be  observed  that 
the  amount  of  iron  is  strikingly  large,  and  further  that  the  amount 
of  sodium  and  phosphoric  acid  is  smaller  than  that  of  potassium 
and  chlorine.  The  amount  of  iron  in  new-born  and  young  ani- 
mals is  small  (Lapicque),  in  adults  more  appreciable,  and  in  old 
animals  sometimes  considerable.  Nasse  found  nearly  50  p.  m.  in 
the  dried  pulp  of  the  spleen  of  an  old  horse. 

The  quantitative  analyses  of  the  human  spleen  by  Oidtmann^ 
give  the  following  results :  In  men  he  found  750-694  p.  m.  water 
and  250-306  p.  m.  solids.  In  that  of  a  woman  he  found  774.8  p.  m. 
water  and  225.2  p.  m.  solids.  The  quantity  of  inorganic  bodies 
was  in  men  4.9-7.4  p.  m.,  and  in  women  9.5  p.  m. 

In  regard  to  the  pathological  processes  going  on  in  the  spleen 


132  PHYSIOLOGICAL   CHEMISTBT. 

we  must  specially  recall  the  abundant  re-formation  of  leucocytes  in 
leucaemia  and  the  appearance  of  amyloid  substance  (see  page  39). 

Ttie  physiological  functions  of  the  spleen  are  little  known» 
Some  consider  the  spleen  as  a  melting  organ  o£  the  red  blood-cor- 
puscles (KoLLiKER,  Eckee),  and  the  occurrence  of  the  above-men- 
tioned iron  deposit  seems  to  confirm  this  view.  Some  (Geelach, 
FuNKE,  and  others)  regard  the  spleen  as  a  blood-forming  organ. 
Other  investigators  consider  that  steps  in  the  modelling  of  the  red 
blood-corpuscles  occur  in  the  spleen  or  that  young  red  blood-cor- 
puscles occur  in  the  blood  of  the  splenic  vein. 

The  spleen  has  also  been  claimed  to  play  an  important  part  in 
digestion.  The  organ  is  known  to  enlarge  after  a  meal,  and  this 
enlargement  is  thought  by  Schiff  and  Heezbk  to  be  dependent 
upon  the  filling  of  the  pancreas  with  enzymes.  According  to  the 
above-mentioned  investigators,  after  the  extirpation  of  the  spleen 
the  pancreas  does  not  produce  any  enzyme,  which  digests  albumin, 
but  Heidenheim  and  Ewald  have  not  been  able  to  confirm  this 
fact.  According  to  later  investigations  of  Heezen",  an  enzyme 
which  digests  albumin  is  produced  in  the  spleen  during  its  enlarge- 
ment. 

An  increase  in  the  quantity  of  uric  acid  eliminated  occurs  in  leu- 
caemia (Eanke,  Salkowski,  Fleischee  and  Penzoldt,  and  Stadt- 
hagen),  while  the  reverse  ol  this  takes  place  under  the  influence 
of  quinine,  which  produces  an  enlargement  of  the  spleen.  We  have 
here  a  rather  positive  proof  that  there  is  a  close  relationship  between 
the  spleen  and  the  formation  of  uric  acid.  If  we  assume  that  the 
xanthin  bodies  are  steps  to  the  formation  of  uric  acid,  then  the  in- 
crease in  the  uric  acid  in  leucaemia  may  perhaps  depend  on  the  in- 
creased amount  of  xanthin  bodies  (hypoxanthin)  in  the  spleen  in 
this  disease.* 

The  spleen  has  the  same  property  as  the  liver  of  retaining  foreign 
bodies,  metals  and  metalloids. 

The  Thymus  has  been  little  studied.  Besides  proteids  and  sub- 
stances belonging  to  the  connective  group,  we  find  small  quantities 

*  HoKBACZEWSKi  lias  lately  found  in  the  spleeu  the  first  steps  in  the  for- 
mation of  uric  acid,  and  he  has  also  shown  that  when  the  spleen  and  blood  of  a 
calf  are  allowed  to  MCt  onench  other  at  the  temperutureof  the  blood  and  in  the 
presence  of  air,  large  quantities  of  uric  acid  are  formed. 


CHYLE,  LYMPH,  TRAIfSUDATIONS  AND  EXUDATIONS.     133 

of  fat,  leucin,  succinic  acid,  lactic  acid,  and  glucose.  The  large 
quantity  of  xanthin  bodies,  chiefly  adenin,  is  remarkable — 179  p.  m. 
in  the  fresh  gland,  or  19.19  p.  m.  in  the  dried  substance  (Kossel 
and  Schindlee),  Potassium  and  phosphoric  acid  are  the  promi- 
nent mineral  constituents.  Oidtmann  found  807.06  p.  m.  water, 
192.74  p.  m.  organic  and  0.2  p.  m.  inorganic  substances  in  the  gland 
of  a  14-days-old  child. 

The  Thyroid  Gland.  The  chemical  constituents  of  this  gland 
are  little  known.  Bubxow  has  obtained  a  protein  substance  called 
by  him  "  thyreoproteine,"  by  extracting  the  gland  with  common-salt 
solution  or  by  very  dilute  caustic  potash.  This  body  has  about  the 
same  amount  of  nitrogen  but  smaller  amounts  of  carbon  and 
hydrogen  than  the  proteids  in  general.  The  fluid  found  in  the 
vesicle  sometimes  contains  a  mucin-like  substance  which  is  pre- 
cipitated by  an  excess  of  acetic  acid.  Besides  these,  other  sub- 
stances have  been  found  in  the  extract  of  the  glands,  such  as  leucin, 
xanthin,  liyperxantliin,  lactic  and  succinic  acids,  OiDTMANif  found 
in  the  thyroid  gland  of  an  old  woman  822.4  p.  m.  water,  176.7  p.  m. 
organic  and  0.9.  p.  m.  inorganic  substances.  He  found  772.1  p.  m. 
water,  223.4  p.  m.  organic  and  4.5  p.  m.  inorganic  substances  in  an 
infant  14  days  old. 

In  "  STRUMA  CYSTICA  "  Hoppe-Seyler  f ound  hardly  any  albu- 
min in  the  smaller  glandular  vessels,  but  an  excess  of  mucin, 
while  in  the  larger  he  found  a  great  deal  of  albumin,  70-80  p.  m. 
Cholesterin  is  regularly  found  in  such  cysts,  sometimes  in  such  large 
quantities  that  the  entire  contents  form  a  thick  mass  of  cholesterin 
plates.  Crystals  of  calcium  oxalate  also  occur  frequently.  The 
contents  of  the  struma  cysts  are  sometimes  of  a  brown  color  due 
to  decomposed  coloring  matter,  methaemoglobin  (and  haematin  ?). 
Bile-coloring  matters  have  also  been  found  in  such  cysts.  (In  regard 
to  the.  paralbumins  and  colloids  which  have  been  found  in  struma 
cysts  and  colloid  degeneration,  see  Chapter  XI.) 

Little  is  known  in  regard  to  the  functions  of  the  thyroid  gland. 
From  a  chemical  standpoint  the  view  is  worth  suggesting  that  the 
so-called  myxoedema,  which  is  a  slimy  infiltration  of  the  subcuta- 
neous cell-tissue  of  the  head  and  throat  (besides  other  disturbances) 
stands  in  connection  with  the  failing  of  the  activity  of  the  thyroid 
gland.    HoRSLEY  and  Halliburton  found  in  monkeys,  but  not  in 


134  PHTSIOLOGICAL   CHEMISTRT. 

pigs,  that  the  amount  of  mucin  in  the  tissue  was  increased  after 
extirpating  the  thyroid  gland. 

The  Suprarenal  Body.  Besides  proteids,  substances  of  the 
connective  tissue  and  salts,  we  have  found  in  the  suprarenal 
body  palmitin,  lecithin,  neurin,  and  glycero-phosphoric  acid,  which 
last  gives  the  poisonous  properties  of  the  watery  extract  of  the 
gland  (Marino-Zuco  and  Guarnieri),  and  some  leucin,  which  is 
probably  a  decomposition  product.  The  statement  that  benzoic  acid, 
hippuric  acid,  hiliary  acids,  and  taurin  occur  in  this  gland  requires 
further  confirmation.  In  the  medulla  there  have  been  found  one 
or  more  chromogens  which  are  converted  into  a  red  coloring  mat- 
ter by  the  action  of  the  air,  light,  warmth,  haloid  or  metallic  salts 
(VuLPiAN,  Krukeistberg).  Pyrocatechin  also  probably  occurs 
therein.  Because  of  the  amount  of  chromogen  contained  in  the 
suprarenal  body,  a  connection  is  claimed  between  the  abnormal 
deposition  of  pigment  in  the  skin,  which  is  characteristic  of  Addi- 
son's disease,  and  the  diseased  changes  which  often  occur  in  the 
suprarenal  body. 


CHAPTER  VI. 


THE   LIVER. 


The  liver,  which  is  the  largest  organ  of  the  body,  stands  in 
close  relationship  to  the  blood-forming  organs.  The  imiaortance 
of  this  organ  in  the  jDhysiological  composition  of  the  blood  is  evi- 
dent from  the  fact  that  the  blood  coming  from  the  digestive  tract, 
laden  with  absorbed  bodies,  must  circulate  through  the  liver  before 
it  is  driven  by  the  heart  through  the  different  organs  and  tissues. 
It  has  been  proved,  at  least  for  the  carbohydrates,  that  an  assimila- 
tion of  the  absorbed  nutritive  bodies  which  are  brought  to  the 
liver  by  the  blood  of  the  portal  vein  takes  place  in  this  organ. 
The  occurrence  of  synthetical  processes  in  the  liver  has  been  posi- 
tively proved  by  special  observations.  It  is  possible  that  in  the  liver 
certain  ammonia  combinations  are  converted  into  urea  or  uric  acid 
(in  birds),  while  certain  products  of  putrefaction  in  the  intestines, 
such  as  phenol,  may  be  converted  by  synthesis  into  ethereal  sul- 
phuric acids  by  the  liver  (Pflugek  and  Kochs).  The  liver  has 
also  the  property  of  removing  and  retaining  heterogeneous  bodies 
from  the  blood,  and  this  is  not  only  true  of  metallic  salts,  which  are 
often  retained  by  this  organ,  but  also,  as  Schiff,  Lautenberger, 
Jacques,  Heger,  and  Eoger  have  shown,  the  alkaloids  are  re- 
tained and  are  probably  partially  decomposed  in  the  liver. 

Even  though  the  liver  is  of  assimilatory  importance  and  purifies 
the  blood  coming  from  the  digestive  tract,  it  is  at  the  same  time  a 
secretory  organ  which  eliminates  a  specific  secretion,  the  bile,  in 
the  production  of  which  the  red  blood-corpuscles  are  destroyed,  or 
at  least  one  of  their  constituents,  the  haemoglobin,  is  transformed. 
It  is  generally  admitted  that  the  liver  acts  contrariwise  during  foetal 
life,  at  that  time  forming  the  red  blood-corpuscles. 

135 


136  PHYSIOLOGICAL   CHEMISTRY. 

There  is  no  doubt  that  the  chemical  operations  going  on  in  this 
organ  are  manifold  and  must  be  of  the  greatest  importance  for  the 
•organism;  but  unfortunately  we  know  very  little  about  the  kind 
and  extent  of  these  processes.  Among  them  are  two  principal 
•ones  which  will  be  fully  treated  in  this  chapter,  after  we  have 
first  described  the  constituents  and  the  chemical  composition  of  the 
liver.  One  of  these  processes  seems  to  be  of  an  assimilatory  nature 
and  refers  to  the  formation  of  glycogen,  while  the  other  refers  to 
the  production  and  secretion  of  the  bile. 

The  reaction  of  the  liver-cell  is  alkaline  during  life,  but  becomes 
acid  after  death.  This  change  is  probably  due  to  the  formation  of 
lactic  acid,  causing  a  coagulation  of  the  albumins  of  the  protoplasm 
of  the  cell.  A  positive  difference  between  the  albuminous  bodies 
of  the  dead  and  the  living,  non-coagulated  protoplasm  has  not  been 
observed. 

The  albuminous  bodies  of  the  liver  were  first  carefully  investi- 
gated by  Plos'z.  He  found  in  the  watery  extract  of  the  liver  an 
albuminous  substance  which  coagulates  at  +  45°  C,  also  a.  globulin 
which  coagulates  at  +  75°  C,  a  nucleo-albumin  (?)  which  coagu- 
lates at  +  70°  C,  and  lastly  an  albuminous  body  which  is  nearly 
related  to  coagulated  albumin  and  which  is  insoluble  in  dilute 
acids  at  the  ordinary  temperature,  but  dissolves  on  the  application 
of  heat,  being  converted  into  an  albuminate.  St.  Zaleski  found 
in  the  liver  an  albuminous  body  containing  iron,  in  which  the  iron 
is  more  or  less  strongly  combined,  but  it  is  unknown  what  relation 
this  bears  to  the  albuminous  bodies  isolated  by  Plos'z. 

The  fat  of  the  liver  occurs  partly  as  very  small  globules  and 
partly,  especially  in  nursing  children  and  sucking  animals,  as  also 
after  food  rich  in  fat,  as  rather  large  fat-drops.  This  infiltration 
of  fat,  which  may  be  made  so  abundant  by  proper  food  that  it  ap- 
pears similar  in  the  highest  degree  to  a  pathological  fatty  liver, 
begins  in  the  periphery  of  the  acini  and  extends  towards  the  cen- 
tre. If  the  amount  of  fat  in  the  liver  is  increased  by  an  infiltra- 
tion, the  water  decreases  correspondingly,  while  the  quantity  of  the 
other  solids  remains  little  changed.  In  fatty  degeneration  this  is 
different.  In  this  process  the  fat  is  formed  from  the  protoplasm 
of  the  cell,  and  the  quantity  of  the  other  solids  is  therefore  dimin- 
ished while  the  amount  of  water  is  only  slightly  changed.     To 


THE  LIVER.  137 

illustrate  this,  we  give  below  the  results  from  a  normal  liver,  and 
also  the  results  obtained  by  Perls  in  fatty  degeneration  and  fatty 
infiltration.     The  results  are  in  1000  parts. 

Water.  Fat.  Remaining  Solids. 

Normal  liver 770  20-35            2U7-195 

Fatty  degeneration 810  87                   97 

Fatty  inliltration 620  190-240          184-145 

Among  the  extractive  sulstances  besides  glycogen,  which  will 
be  treated  of  later,  we  find  rather  large  quantities  of  xanthin 
bodies.  Kossel  found  in  1000  parts  of  the  dried  substance  1.97 
p.  m.  guanin,  1.3-4  p.  m.  liypoxantliin,  and  1.21  p.  m.  xanthin. 
Adenin  is  also  contained  in  the  liver.  In  addition  there  have  been 
found  urea  and  uric  acid  (especially  in  birds),  and  indeed  in  larger 
quantities  than  in  the  \Aoo^,  paralactic  acid,leucin,jecorin,  and, 
in  pathological  cases,  inosit,  tyrosin,  and  cystin.  The  occurrence 
of  hile-coloring  matters  in  the  liver-cell  under  normal  conditions  is 
doubtful  ;  but  in  retention  of  the  bile  the  cells  may  absorb  the 
coloring  matter  and  become  colored  thereby. 

Jecorin  was  first  found  by  Dkechskl  in  the  liver  of  a  horse,  and  later  by 
Baldi  in  the  liver  and  spleen  of  other  animals,  in  the  muscles  and  blood 
of  the  horse,  and  in  the  human  brain.  It  contains  sulphur  and  phosphorus, 
but  its  constitution  is  not  positively  known.  Jecorin  dissolves  in  ether,  but  is 
precipitated  from  this  solution  by  alcohol.  It  reduces  copper  oxide,  and  it 
solidities  after  boiling  with  alkalies  to  a  gelatinous  mass.  It  may  lead  to  errors 
in  the  investigations  of  organs  or  tissues,  for  it  can  easily  be  mistaken  for 
lecithin  on  account  of  its  solubilities  and  because  it  contains  phosphorus. 

The  mineral  ladies  of  the  liver  consist  of  phosphoric  acid, 
potassium,  sodium,  alkaline  earths,  and  chlorine.  The  potassium 
is  in  excess  of  the  sodium.  Iron  is  a  regular  constituent  of  the 
liver,  but  in  very  variable  amounts,  0.3-11.8  p.  m.  calculated  for 
the  dried  substance  of  the  liver  (St.  Zaleski).  A  part  of  the 
iron  exists  as  phosphate,  and  the  greater  part  in  combination  with 
the  protein  bodies  (St.  Zaleski).  Copper  seems  to  be  a  physio- 
logical constituent.  Foreign  metals,  such  as  lead,  zinc,  and  others, 
are  easily  taken  up  and  retained  for  a  long  time  by  the  liver. 

V.  BiBRA  found  in  1000  parts  of  the  liver  of  a  young  man  who 
had  suddenly  died  762  p.  m.  water  and  238  p.  m.  solids,  consist- 
ing of  25  p.  m.  fat,  152  p.  m.  albumin  and  gelatine-forming  sub- 
stance, and  61  p.  m.  extractive  substances. 


138  PHYSIOLOGICAL   CHEMISTRY. 

Glycogen  and  the  Glycogen  Formation. 

Glycogen  was  discovered  in  1857  by  Beetjtard  and  Hexsek  in- 
dependently of  each  other.  It  is  a  carbohydrate  closely  related  to  the 
starches  or  dextrins  with  the  general  formula  CeHioOj,  perhaps 
6(C6Hio05)  +  H2O  (KuLZ  and  Boentragee).  The  largest  quanti- 
ties are  found  in  the  liver  of  full-grown  animals  (Beexaed,  Hex- 
SEK,  and  others),  and  smaller  quantities  in  the  muscles  (Nasse, 
Brucke,  and  others).  It  is  found  in  very  small  quantities  in  many 
organs,  such  as  the  lungs,  skin,  the  sheath  of  the  roots  of  the  hair 
(WiEESMA,  Baefuth),  the  middle  coat  of  the  arteries,  and  also  in 
certain  epithelial  cells  (Schiele,  Wieesma).  Its  occurrence  in 
lymphoid  cells  and  in  j)us  has  been  mentioned  in  the  previous 
chapter.  Glycogen  has  been  shown  by  Beexard  and  KiJHXE  to  be 
very  widely  diffused  in  the  embryonic  tissue,  and  it  seems  habitually 
to  be  a  constituent  of  tissues  in  which  a  rapid  cell-formation  and 
cell-development  is  taking  place  (Hoppe-Setlee).  It  is  also 
present  in  rapidly-formed  pathological  swellings  (Hoppe-Seyler). 
It  has  been  found  in  several  organs  in  diabetes  mellitus.  Glycogen 
is  also  found  in  the  plant  kingdom  in  the  myxomycetas. 

The  quantity  of  glycogen  in  the  liver,  as  also  in  the  muscles,  de- 
pends essentially  upon  the  food.  In  starvation  it  disappears  after 
a  short  time,  but  more  rapidly  in  small  than  in  large  animals.  Ac- 
cording to  the  old  views  (LuchsijSTGee),  it  disappears  earher  from 
the  muscles  than  from  the  liver;  but  according  to  more  modern 
views  (Aldehoff),  the  reverse  of  this  takes  place.  After  partaking 
of  food  especially  rich  in  carbohydrates,  the  liver  becomes  rich 
again  in  glycogen,  the  greatest  increment  occurring  14  to  16  hours 
after  eating  (KuLz).  The  quantity  of  glycogen  in  the  liver  may 
be  100-120  p.  m.  or  indeed  even  more  after  the  consumption  of 
food  rich  in  carbohydrates.  Ordinarily  it  is  considerably  less  or 
12-30  to  40  p.  m. 

Glycogen  forms  an  amorphous,  white,  tasteless,  and  inodorous 
powder.  It  gives  an  opalescent  solution  with  water  which,  when  al- 
lowed to  evaporate  in  the  water-bath,  forms  a  pellicle  over  the  surface 
that  disappears  again  on  cooling.  The  solution  is  dextro-gyrate, 
[a)  D  =  +  211°  (KiJLz).  The  specific  rotary  power  is  given  somer 
what  differently  by  various  investigators.     A  solution  of  glycogen 


THE  LIVEB.  139 

is  colored  wine-red  by  iodine.  It  may  hold  copper  oxyhydrate  in 
solution  in  alkaline  liquids,  but  does  not  reduce  it.  A  solution  of 
glycogen  in  water  is  not  precipitated  by  potassium-mercuric  iodide 
and  hydrochloric  acid,  but  is  precipitated  by  alcohol  or  ammoniacal 
lead  acetate.  Glycogen  seems  to  be  changed  somewhat  by  prolonged 
boiling  with  dilute  caustic  potash  (Vintschgau  and  Dietl).  It  is 
converted  into  glucose  by  diastatic  enzymes  and  also  by  being  boiled 
with  dilute  mineral  acids. 

The  preparation  of  pure  glycogen  (simplest  from  the  liver)  is 
generally  performed  by  the  method  suggested  by  Bruckb,  of  which 
the  main  points  are  the  following:  Immediately  after  the  death  of 
the  animal  the  liver  is  thrown  into  boiling  water,  then  finely  divided 
and  boiled  several  times  with  fresh  water.  The  filtered  extract  is 
now  sufficiently  concentrated,  allowed  to  cool,  and  the  albumin 
removed  by  alternately  adding  potassium-mercuric  iodide  and 
hydrochloric  acid.  The  glycogen  is  precipitated  from  the  filtered 
liquid  by  the  addition  of  alcohol  until  the  liquid  contains  60  vols, 
per  cent.  Tlie  glycogen  is  first  washed  on  the  filter  with  60^  and 
then  with  95^  alcohol,  then  treated  with  ether  and  dried  over 
sulphuric  acid.  It  is  always  contaminated  with  mineral  substances. 
To  be  able  to  extract  the  glycogen  from  the  liver  or  especially  from 
muscles  and  other  tissues  completely,  which  is  essential  in  a  quanti- 
tative estimation,  these  parts  must  first  be  boiled  for  a  few  hours 
with  a  dilute  solution  of  caustic  potash,  say  4  gms.  KOH  to  100  gms. 
liver  (KiJLz). 

The  quantitative  determination  is  ordinarily  performed  accord- 
ing to  the  above  method  of  Brucke,  but  care  must  be  taken  that 
the  precipitate  obtained  by  the  potassium-mercuric  iodide  and  hydro- 
chloric acid  is  removed  at  least  four  times  from  the  filter  and  stirred 
with  water  to  which  has  been  added  a  few  drops  of  hydrochloric 
acid  and  potassium-mercuric  chloride,  and  refiltered  so  as  to  be  cer- 
tain that  all  the  glycogen  is  obtained  in  the  filtrate  (KtJLz).  The 
quantity  of  glycogen  may  also  be  determined  by  the  polariscope  or 
by  titration  after  first  converting  the  glycogen  into  glucose  by  boil- 
ing with  an  acid. 

Numerous  investigators  have  endeavored  to  determine  the  origin 
of  glycogen  in  the  body.  The  quantity  of  glycogen  in  the  liver  is 
increased  after  partaking  of  many  substances,  in  the  first  place  by 
the  varieties  of  sugar  and  several  other  carbohydrates  (Pavy  and 
others),  also  by  glycerin  (van  Been,  Weiss,  Luchsin"GEr),  gelatin 
(Woroschiloff),  and  the  glucoside  arbutin.  Inosit  (Kulz)  and 
mannit  (Luchsinger)  have,  on   the  contrary,  no  action.     Fat  is 


140  PHTSIOLOGIGAL   CHEMISTRY. 

claimed  by  most  investigators  to  have  no  influence.  The  views  in 
regard  to  the  importance  of  the  proteids  in  the  glycogen  formation 
are  somewhat  divided.  From  many  observations,  particularly  certain 
nutrition  experiments  with  boiled  meat  (ISTAUisrYN)  or  blood-fibrin 
(v.  Merings),  there  is  no  doubt  that  the  proteids  are  concerned  in 
the  formation  of  glycogen.  Wolefberg  has  also  found  that  he 
obtained  a  larger  glycogen  production  from  a  diet  of  proteids  and 
carbohydrates  in  proper  proportions  than  from  a  diet  consisting  only 
of  carbohydrates  with  very  little  proteids.  It  has  been  shown  by 
many  observers,  and  lately  also  by  Moszeik,  that  a  diet  of  proteids 
with  carbohydrates  caused  a  greater  increase  in  the  glycogen  than  a 
diet  of  carbohydrates  alone. 

The  great  importance  of  the  carbohydrates  in  the  formation  of 
glycogen  has  given  rise  to  the  opinion  that  the  glycogen  in  the  liver 
is  produced  from  other  carbohydrates  (glucose)  by  a  synthesis  with 
the  separation  of  water  with  a  formation  of  anhydride  (Luchsin- 
GER  and  others).  This  theory  {anhydride  theory)  has  found  oppo- 
nents because  it  neither  explains  the  formation  of  glycogen  from  such 
different  bodies  as  albumin,  carbohydrates,  glycerine,  and  others,  nor 
the  circumstance  that  the  glycogen  is  always  the  same,  independent 
of  the  properties  of  the  carbohydrate  introduced,  whether  it  is  dex- 
tro-  or  Isevo-gyrate.  It  is  therefore  the  opinion  of  many  investi- 
gators that  all  glycogen  is  formed  from  proteid,  and  that  this  splits 
into  two  parts,  one  containing  nitrogen  and  the  other  free  from 
nitrogen:  the  latter  is  the  glycogen.  According  to  these  views,  the 
carbohydrates  act  only  in  that  they  spare  the  proteid  and  the  gly- 
cogen produced  therefrom  (Weiss,  Wolffberg,  and  others). 

In  many  animal  tissues  we  have  proteids  from  which  carbohy- 
drates or  closely-related  bodies  may  be  split  off.  The  occurrence  in 
the  liver  of  such  proteids,  from  which  carbohydrates  can  be  split 
off,  is  from  certain  observations  not  at  all  improbable,  but  still  it 
has  not  been  fully  proved.  Nor  has  the  view  of  certain  investigators, 
that  in  the  ordinary  sense  we  have  a  carbohydrate  group  preformed 
in  the  albuminous  body,  been  conclusively  established.  Under  such 
circumstances  it  is  not  easy  to  explain  the  formation  of  glycogen  in 
the  animal  body  from  proteids.  But  as  it  seems  to  be  certain  that 
glycogen  can  be  produced  either  from  proteids  or  from  carbo- 
hydrates, which  has  lately  been  further  demonstrated  by  E.  Voix, 


THE  LIVER.  141 

the  opinion  expressed  by  Pflugee  has  unquestionably  been  mis- 
leading. As  the  fat  may  be  formed  partly  from  proteids  and  partly 
from  carbohydrates  by  a  synthesis  after  previous  splitting,  Pfluger 
claims  that  the  glycogen  in  the  liver  may  also  be  produced  from  dif- 
ferent substances  by  a  complex  splitting  and  synthesis.  There  is 
no  doubt  that  the  glycogen  of  the  liver,  which  surrounds  the  nu- 
cleus of  the  liver-cells  as  amorphous  masses,  is  formed  in  these  cells. 
Where  does  the  glycogen  occurring  in  the  other  organs,  such  as  the 
muscles,  originate  ?  Is  the  glycogen  of  the  muscles  formed  on  the 
spot  or  is  it  transmitted  from  the  liver  to  the  muscles  by  means  of 
the  blood?  These  questions  cannot  yet  be  answered  with  positive- 
ness,  and  the  investigations  on  this  subject  by  different  experimen- 
ters (on  frogs  by  KiJLZ  and  on  birds  by  Laves  and  Minkowsky) 
have  given  contradictory  results. 

Glycogen  is  considered  as  a  reserve  nutritive  substance  deposited 
in  the  liver,  and,  according  to  the  ordinary  view,  it  is  transported 
by  the  blood  from  the  liver  to  the  other  organs,  especially  to  the 
muscles,  where  it  serves  as  a  source  of  material  for  work.  The  im- 
portance of  glycogen  in  the  formation  of  heat  follows  from  the  fact 
that  on  cooling  the  animal  body  the  glycogen  is  quickly  exhausted. 
The  possibility  that  fats  may  be  formed  from  glycogen,  as  well  as 
from  other  carbohydrates,  cannot  be  denied. 

The  relationship  of  glycogen  to  the  formation  of  sugar  is  of  spe- 
cial interest.  In  a  dead  liver  the  glycogen  is  rapidly  converted  into 
sugar,  and  this  fact  naturally  leads  to  the  supposition  that  we  have 
a  sugar  formation  from  glycogen  in  the  liver  during  life  under  nor- 
mal conditions,  a  vitale  Glyhogenie  (author).  As  proof  of  this,  Cl. 
Bernard  has  found  that  the  liver,  under  physiological  conditions, 
always  contains  some  sugar,  and  also  that  the  blood  from  the  hepatic 
vein  is  always  somewhat  richer  in  sugar  than  the  blood  from  the 
portal  vein.  The  correctness  of  either  or  both  of  these  statements 
has  been  disputed  by  many  investigators,  such  as  Pavy,  Ritter, 
ScHiFF,  Eulenberg,  Lussana,  Abeles  and  others.  It  is  not 
denied  that  the  blood  from  the  hepatic  vein  may  not  contain  some- 
what more  sugar  under  certain  circumstances,  but  it  is  probably  due 
to  the  result  of  the  experiment. 

It  is  impossible  to  discuss  more  completely  the  numerous  works 
which  treat  of  this  question,  and  it  is  perhaps  sufficient  to  say  here 


142  PHYSIOLOGICAL   CHEMISTRT. 

that  the  two  above-mentioned  opinions  stand  to-day  in  opposition 
to  each  other.  The  existence  of  a  vital  formation  of  sugar  from 
the  glycogen  of  the  liver  is  denied  by  certain  investigators,  but  ad- 
mitted by  others.  Those  who  admit  this  formation  claim  that  it  is 
produced  by  the  action  of  an  enzyme  which  is  formed  in  the  blood, 
especially  on  the  destruction  of  the  red  blood-corpuscles  (Tiegel). 
Other  investigators,  such  as  Forster,  Eves,  Dastre  and  others, 
deny  the  action  of  an  enzyme,  and  are  of  the  opinion  that  the  for- 
mation of  sugar  is  produced  by  a  vital  action  of  the  protoplasm  of 
the  living  cell. 

Seegek  claims  that  the  sugar  formation  in  the  liver  occurs  on  a 
very  large  scale  under  physiological  conditions,  and  that  the  blood 
of  the  hepatic  vein  is  considerably  richer  in  sugar  than  the  blood 
of  the  portal  vein.  He  also  claims  that  the  sugar  is  not  formed 
from  the  glycogen,  but  from  the  peptones  and  fat.  The  observa- 
tions which  form  the  basis  of  this  theory  have  not  been  confirmed 
by  other  investigators  (CHiTTEifDEN"  and  Lambert). 

The  question  as  to  a  physiological  formation  of  sugar  in  the 
liver  is  disputable  and  not  settled.  There  is  no  doubt  that  in  cer- 
tain lesions  of  the  nervous  system,  by  poisoning,  etc.,  an  abundant 
formation  of  sugar  may  appear,  which,  at  least  in  certain  cases,  is 
derived  from  the  glycogen  of  the  liver,  and  several  investigators 
consider  with  Cl.  Bernard  this  sugar  formation  as  well  as  the 
elimination  sugar  in  diabetes  mellitus,  as  an  increase  in  the  normal 
formation  of  sugar  from  the  glycogen. 

A  discussion  of  the  different  views  in  regard  to  glycosuria 
and  diabetes  mellitus  is  beyond  the  plan  and  scope  of  this 
book.  The  appearance  of  glucose  in  the  urine  is  a  symptom 
which  under  different  conditions  may  have  essentially  different 
causes.  Under  all  circumstances  it  is  necessary  to  carefully  differ- 
entiate between  those  diseased  conditions  on  the  one  side  which 
are  grouped  under  the  name  diabetes  mellitus  and  the  experi- 
mental production  of  glycosuria  on  the  other  side.  In  diabetes,  at 
least  in  most  cases,  we  are  more  probably  dealing  with  a  decreased 
burning-up  of  sugar  in  the  organism  than  an  increased  production 
of  sugar  from  the  glycogen  of  the  liver,  or  a  disturbed  storing-np 
of  glycogen  in  this  organ.  On  the  contrary,  in  experimental  gly- 
cosuria in  certain  cases  we  have  undoubtedly  a  formation  of  sugar 


THE  LIVER.  143 

from  the  glycogen  of  the  liver.  As  proof  thereof,  in  the  so-called 
"  Zuckerstich  "  (lesion  of  a  certain  part  of  the  fourth  ventricle  of 
the  brain)  no  glycosuria  is  produced  in  animals  with  glycogen-free 
livers  (fasting  animals),  while  in  livers  containing  glycogen  it  is 
found  rapidly  disappearing  with  the  formation  of  sugar  after  this 
operation  (Hermann  and  Dock,  Luchsingek).  Von  Merings 
has  shown  by  experiments  that  we  may  have  a  glycosuria  formed 
independently  of  the  glycogen  of  the  liver.  This  investigator  has 
shown  by  experiments  on  dogs  that  in  animals  which  have  been 
starving  for  some  time,  so  that  the  liver,  as  well  as  the  muscles,  is 
free  from  glycogen,  a  very  considerable  glycosuria  is  produced  on 
administering  the  glucoside  phloridzin.  The  elimination  of  sugar  is 
considerably  greater  by  this  means  than  that  produced  by  the  de- 
composition of  the  glucoside  itself.  Von  Merings  has  been  able 
to  produce  diabetes  by  this  glucoside  in  geese  which  have  had  their 
livers  removed  ;  and  Langendorff  has  also  produced  the  same  in 
frogs  whose  livers  had  been  extirpated.  In  the  so-called  phloridzin 
diabetes  the  sugar  is  not  formed  from  the  glycogen  of  the  liver,  but 
to  all  appearances  from  the  albumin  (or  proteids). 

The  Bile  and  its  Formation. 

By  the  employment  of  a  biliary  fistula,  an  operation  which  was 
first  performed  in  1844  by  Schwann,  it  is  possible  to  study  the 
secretion  of  the  bile.  This  secretion  takes  place  at  a  very  low 
pressure;  therefore  an  apparently  unimportant  hindrance  in  the 
outflow  of  the  bile,  namely,  a  stoppage  of  mucus  in  the  exit  or  the 
secretion  of  large  quantities  of  viscous  bile,  may  cause  stagnation 
and  absorption  of  the  bile  by  means  of  the  lymphatic  vessels  (ab. 
sorption  icterus). 

The  quantity  of  bile  secreted  during  a  specified  time,  say  24 
hours,  is  rather  difficult  to  determine  with  accuracy.  The  approxi- 
mate amount  for  the  dog,  as  determined  by  Bidder  and  Schmidt, 
is  about  20  grms.,  with,  in  round  numbers,  1  grm.  of  solids  per  kilo  of 
the  weight  of  the  body.  For  human  beings  Kanke  has  calculated 
an  average  of  14  grms.,  with  0.44  grms.  solids.  The  amount  is  de- 
pendent upon  the  nutrition.  In  fasting  the  quantity  decreases, 
but  increases  after  taking  food.    The  statements  are  contradictory  in 


144  PHYSIOLOGICAL   CHEMISTRY. 

regard  to  the  time  necessary  after  partaking  of  food  before  the 
secretion  reaches  its  maximum.  Formerly  it  was  held  that  the  secre- 
tion of  bile  is  increased  by  food  rich  in  albumin  ;  in  later  investi- 
gations, by  Rosenberg,  it  was  found,  on  the  contrary,  that  the  fats 
give  a  greater  stimulus  to  the  secretion  of  bile  than  do  the  other 
nutritive  substances.  The  drinking  of  water  increases  the  secretion 
of  bile.  The  statements  of  different  investigators  vary  so  much  in 
regard  to  the  action  of  different  medicinal  bodies  in  the  secretion  of 
bile  that  it  is  impossible  to  reach  any  conclusion  on  the  subject. 
All  investigators  who  have  worked  on  this  subject  seem  to  agree 
that  sodium  salicylate  is  a  true  cathartic  (Rutherford,  Vignal, 
Lewaschew,  Prevost  and  Binet,  Rosenberg).  Also  turpentine, 
which  is  a  component  of  the  so-called  Durand's  remedy,  seems  to 
increase  the  secretion  (Lewaschew,  Prevost  and  Binet,  Rosen- 
berg). Olive-oil  is  a  very  active  cathartic  (Rosenberg).  ,  By  the 
increased  secretion  of  bile  the  amount  of  solids  does  not,  as  a  rule, 
increase  at  the  same  rate  as  the  water,  and  the  concentration  of  the 
bile  decreases.  An  exception  to  this  is  found  only  in  the  influence 
exerted  by  the  bile  itself,  acting  as  it  does  as  a  powerful  catliartic 
by  which  also  the  concentration  of  the  secreted  bile  is  increased. 

The  bile  is  a  mixture  of  the  secretion  of  the  liver-cells  and  the 
so-called  mucus  which  is  secreted  by  the  glands  of  the  biliary 
passages  and  by  the  mucous  membrane  of  the  gall-bladder.  The 
secretion  of  the  liver,  which  is  generally  poorer  in  solids  than  the 
bile  from  the  gall-bladder,  is  thin  and  clear,  while  the  bile  collected 
in  the  gall-bladder  is  more  ropy  and  viscous  on  account  of  the  ab- 
sorption of  water  and  the  admixture  of  "mucus,"  and  cloudy 
because  of  the  admixture  of  cells,  pigments,  and  the  like.  The 
specific  gravity  of  the  bile  from  the  gall-bladder  varies  consider- 
ably, in  man  between  1.010  and  1.040.  Its  reaction  is  alkaline. 
The  color  changes  in  different  animals:  golden  yellow,  yellowish 
brown,  olive-brown,  brownish  green,  grass-green,  or  bluish  green. 
Bile  obtained  from  an  executed  person  immediately  after  death 
is  golden  yellow  or  yellow  with  a  shade  of  brown.  Still  cases  occur 
in  which  fresh  human  bile  has  a  green  color.  The  ordinary 
post-mortem  bile  has  a  variable  color.  The  bile  of  certain  animals 
has  a  peculiar  odor;  as  example,  ox-bile  has  an  odor  of  musk,  espe- 
cially on  warming.     The  taste  of  bile  is  also  different  in  different 


THE  LIVER.  145 

animals.  Human  as  well  as  ox  bile  has  a  bitter  taste  with  a  sweetish 
after- taste.  The  bile  of  the  pig  and  rabbit  has  an  intense  persistent 
bitter  taste.  On  heating  bile  to  boiling  it  does  not  coagulate.  It 
contains  (in  the  ox)  only  traces  of  true  mucin,  and  its  ropy  proper- 
ties depend,  it  seems,  chiefly  on  the  presence  of  a  nucleoalbumin 
similar  to  mucin  (Paijkull).  The  specific  constituents  of  the  bile 
are  bile-acids  combined  with  alkalies,  bile-pigments,  and  besides 
small  quantities  of  lecithin,  cliolesterin,  soajjs,  neutral  fats,  urea,a,nd 
mineral  substances  (sodium  chloride,  calcium  and  magnesium  phos- 
phate, and  iron). 

Bile-salts.  All  bile-acids  can  be  divided  into  two  groups,  the 
glycocliolic-  and  the  taurocliolic-acid  groups.  All  glycocholic  acids 
contain  nitrogen,  but  are  free  from  sulphur  and  can  be  split  with 
the  addition  of  water  into  glycocoll  (amido-acetic  acid)  and  an 
acid  free  from  nitrogen,  cholalic  acid.  All  taurocholic  acids  con- 
tain nitrogen  and  sulphur  and  are  split,  with  the  addition  of  water, 
into  taurin  (amido-isethionic  acid)  containing  sulphur  and  cholalic 
acid.  The  reason  of  the  existence  of  different  glycocholic  and  tau- 
rocholic acids  depends  on  the  fact  that  there  are  several  cholalic 
acids. 

The  different  bile-acids  occur  in  the  bile  as  alkali  salts,  generally 
in  combination  with  sodium,  but  in  sea-fishes  as  potassium  salts. 
In  the  bile  of  certain  animals  we  find  almost  solely  glycocholic  acid, 
in  others  only  taurocholic  acid,  and  in  other  animals  a  mixture  of 
both  (see  below). 

All  alkali  salts  of  the  biliary  acids  are  soluble  in  water  and  alco- 
hol, but  insoluble  in  ether.  Their  solution  in  alcohol  is  therefore 
precipitated  by  ether,  and  this  precipitate,  with  the  proper  care  in 
manipulation,  gives,  for  nearly  all  kinds  of  bile  thus  far  investigated, 
rosettes  or  balls  of  fine  needles  or  4-6-sided  prisms  (Plattkee's 
crystallized  bile).  Fresh  human  bile  also  crystallizes  readily.  The 
bile-acids  and  their  salts  are  optically  active  and  dextro-rotary.  The 
former  are  dissolved  by  concentrated  sulphuric  acid  at  the  ordi- 
nary temperature,  forming  a  reddish-yellow  liquid  which  has  a 
beautiful  green  fluorescence.  On  carefully  warming  with  concen- 
trated sulphuric  acid  and  a  little  cane-sugar,  the  bile-acids  give  a 
beautiful  cherry-red  or  reddish-violet  liquid.  Pettenkofek's  reac- 
tion for  bile-acids  is  based  on  these  facts. 


146  PHTSIOLOOICAL    CHEMISTRY. 

Pettenkofer's  test  for  bile-acids  is  performed  as  follows.  A 
small  quantity  of  bile  in  substance  is  dissolved  in  a  small  porcelain 
disli  in  concentrated  sulphuric  acid  and  warmed,  or  some  of 
the  liquid  containing  the  bile-acids  is  mixed  with  concentrated 
sulphuric  acid,  taking  special  care  in  both  cases  that  the  temper- 
ature does  not  rise  higher  than  60-70°  C.  Then  a  10^  solution  of 
cane-sugar  is  added,  drop  by  drop,  continually  stirring  with  a  glass 
rod.  The  presence  of  bile  is  indicated  by  the  production  of  a  beau- 
tiful red  liquid,  whose  color  does  not  disappear  at  the  ordinary 
temperature,  but  becomes  more  bluish  violet  in  the  course  of  a  day. 
This  red  liquid  shows  a  spectrum  with  two  absorption-bands,  the 
one  at  F  and  the  other  between  D  and  E,  near  B. 

This  extremely  delicate  test  fails,  however,  when  the  solution  is 
heated  too  high  or  if  an  improper  quantity — generally  too  much — 
of  the  sugar  is  added.  In  the  last-mentioned  case  the  sugar  easily 
carbonizes  and  the  test  becomes  brown  or  dark  brown.  The  reac- 
tion readily  fails  if  the  sulphuric  acid  contains  sulphurous  acid  or 
the  lower  oxides  of  nitrogen.  Many  other  substances,  such  as  al- 
bumin, oleic  acid,  amylacohol,  morphin,  and  others,  give  a  similar 
reaction,  and  therefore  in  doubtful  cases  the  spectroscopic  exami- 
nation of  the  red  solution  must  not  be  forgotten. 

Pettenkofer's  test  for  the  bile-acids  depends  essentially  on  the 
fact  that  farfurol  is  formed  from  the  sugar  by  the  sulphuric  acid, 
and  this  body  can  therefore  be  substituted  for  the  sugar  in  this  test 
(Mylius).  According  to  Mtlius  and  v.  Udrakszey  a  1  p.  m.  solu- 
tion of  furfurol  should  be  used.  Dissolve  the  bile,  which  must 
first  be  purified  by  animal  charcoal,  in  alcohol.  To  each  c.  c.  of  the 
alcoholic  solution  of  bile  in  a  glass  add  1  drop  of  the  furfurol  solu- 
tion and  1  c.  c.  cone,  sulphuric  acid,  and  cool  when  necessary  so  that 
the  test  does  not  become  too  warm.  This  reaction,  when  per- 
formed as  described,  will  detect  -^ip-jV  milligram  cholalic  acid 
(v.  Udranszky).  Other  modifications  of  Pettenkofer's  test  have 
been  proposed. 

Glycocholic  Acid.  The  constitution  of  that  glycocholic  acid 
occurring  in  human  and  ox  bile,  which  has  been  most  studied  and 
which  is  identical  with  the  cJiolic  acid  of  Strecker  and  Gmelin,  is 
represented  by  the  formula  CagHisNOfi.  Grlycocholic  acid  is  absent 
or   nearly   so  in  the  bile  of  carnivora.     On  boiling  with  acids  or 


THE  LIVER.  147 

alkalies  tliis  acid,  which  is  analogous  to  hippuric  acid,  is  converted 
into  cholalic  acid  and  glycocoll. 

Glycocholic  acid  crystallizes  in  fine,  colorless  needles  or  prisms. 
It  is  soluble  with  difficulty  in  water  (in  about  300  parts  cold  and 
120  parts  boiling  water),  and  is  easily  precipitated  from  its  alkali- 
salt  solution  by  the  addition  of  dilute  mineral  acids.  It  is  readily 
soluble  in  strong  alcohol,  but  with  great  difficulty  in  ether.  The 
solutions  have  a  bitter  but  at  the  same  time  sweetish  taste.  The 
salts  of  the  alkalies  and  alkaline  earths  are  soluble  in  alcohol  and 
water.  The  salts  of  the  heavy  metals  are  mostly  insoluble  or  soluble 
with  difficulty  in  water.  The  solution  of  the  alkali  salts  in  water 
is  precipitated  by  sugar  of  lead,  copper-oxide  and  ferric  salts,  and 
silver  nitrate. 

The  preparation  of  pure  glycocholic  acid  may  be  performed  in 
several  ways.  We  may  precij^itate  the  bile,  which  has  been  freed 
from  mucus  by  means  of  alcohol  and  the  alcohol  removed  by 
evaporation,  by  a  solution  of  lead  acetate.  The  precipitate  is  then 
decomposed  by  a  soda  solution  and  heat,  evaporated  to  dryness,  and 
the  residue  extracted  with  alcohol,  which  dissolves  the  alkali 
glycocholate.  The  alcohol  is  distilled  from  the  filtered  solution  and 
the  residue  dissolved  in  water;  this  solution  is  now  decolorized  by 
animal  charcoal,  and  the  glycocholic  acid  precipitated  from  the 
solution  by  the  addition  of  a  dilute  mineral  acid.  The  acid  may 
be  obtained  in  crystals  either  from  boiling  water,  on  cooling,  or 
from  strong  alcohol  by  the  addition  of  ether.  The  reader  is  re- 
ferred to  more  exhaustive  works  for  other  methods  of  preparation. 

Hyo-glycocholic  Acid,  C27H43N06,  istUe  crystalliue  glycocholic  acid  obtained 
from  the  bile  of  the  pig.  It  is  very  insoluble  in  water.  The  alkali  salts, 
whose  solutions  have  an  intense  bitter  taste  without  any  sweetish  after-taste, 
are  precipitated  by  CaClj ,  BaClj ,  and  MgCU ,  and  may  be  salted  out  like  a 
soap  by  Na2S04  when  added  in  sufficient  quantit}'.  Besides  this  acid  there 
occurs  in  tiie  bile  of  the  pig  still  another  glycocholic  acid  (Jolin). 

The  glycocholate  in  the  bile  of  the  rodent  is  also  precipitated  by  the  above- 
mentioned  salts,  but  cannot,  like  the  corresponding  salt  in  the  human  or  ox 
bile,  be  precipitated  on  saturating  with  a  neutral  salt  (Na2S04).  Guano  bile- 
acid  possibly  belongs  to  the  glycocholic-acid  group,  and  is  found  in  Peruvian 
guano  but  has  not  been  thoroughly  studied. 

Taurocholic  Acid.  This  acid,  which  is  found  in  the  bile  of  man, 
carnivora,  oxen  and  a  few  other  herbivora,  such  as  sheep  and  goats, 
and  which  is  identical  with  the  clwleic  of  Strecker  and  Demar9ay, 
has  the  constitution  C26H45NSO7.  On  boiling  with  acids  and  alka- 
lies it  splits  into  cholalic  acid  and  taurin. 


148  PHYSIOLOGICAL   CHEMI8TRT. 

Taurocholic  acid  may  be  obtained,  though  only  with  difficulty, 
in  fine  needles  which  deliquesce  in  the  air  (Parke).  It  is  very 
soluble  in  water,  and  can  hold  the  difficultly-soluble  glycocholic 
acid  in  solution.  This  is  the  reason  why  a  mixture  of  glycocholate 
with  a  sufficient  quantity  of  taurocholate,  which  often  occurs  in  ox- 
bile,  is  not  precipitated  by  a  dilute  acid.  Taurocholic  acid  is  readily 
soluble  in  alcohol  but  insoluble  in  ether.  Its  solutions  have  a  bitter- 
sweet taste.  Its  salts  are,  as  a  rule,  readily  soluble  in  water,  and 
the  solutions  of  the  alkali  salts  are  not  precipitated  by  copper  sul- 
phate, silver  nitrate,  or  sugar  of  lead.  Basic  lead  acetate  gives,  on 
the  contrary,  a  precipitate  which  is  soluble  in  boiling  alcohol. 

Taurocholic  acid  is  best  prepared  from  decolorized,  crystallized 
dog-bile,  which  contains  only  taurocholate.  The  solution  of  this 
bile  is  precipitated  by  basic  lead  acetate  and  ammonia,- and  the 
washed  precipitate  dissolved  in  boiling  alcohol.  The  filtrate  is  now 
treated  with  H2S,  and  this  filtrate  is  evaporated  at  a  gentle  heat  to 
a  small  volume,  and  treated  with  an  excess  of  water-free  ether. 
The  acid  sometimes  partially  crystallizes. 

Cheno-taurociiolic  Acid.  This  is  the  most  essential  acid  of  goose-bile 
and  has  the  formula  C29H49NSO6.  This  acid,  though  little  studied,  is  known 
to  be  amorphous  and  soluble  in  water  and  alcohol. 

As  repeatedly  mentioned  above,  the  two  bile-acids  split  on 
boiling  with  acids  or  alkalies  into  non-nitrogenized  cholalic  acid 
and  glycocoll  or  taurin.  Therefore  we  will  now  describe  the  prod- 
ucts of  this  splitting. 

Cholalic  Acid.  The  ordinary  cholalic  acid  obtained  as  a  decom- 
position product  of  human  and  ox  bile,  which  occurs  regularly  in 
the  contents  of  the  intestines  and  in  the  urine  in  icterus,  and 
which  is  identical  with  Demar9At's  cliolic  acid,  ha&,  according 
to  Streckee,  and  nearly  all  recent  investigators,  the  constitution 
C24H40O5 ;  but  others  give  as  the  formula  Q^TLi^O^  (Latschinoff). 
According  to  Mtlius,  cholalic  acid  is  a  monobasic  alcohol-acid  with 
a  secondary  and  two  primary  alcohol  groups.   Its  formula  may  there- 

i  CHOH 
fore  be  written  C20H31  \  (CH20II)2.     On   oxidation   it  first  yielda 

(COOH 
dehydrocholalic  acid  (author),  and  then   hilianic  acid  (Cleve), 
The  formulse  of  these  acids  (when  we  take  Cg*  for  the  cholalic  acid) 
are  C24II34O5  aiid  CjiHgiOg.     On  reduction  (in  putrefaction)  cholalic 
acid  may  yield  desoxycUolalic  acid,  O24H40O4  (Mtlius). 


THE  LIVER.  149 

''  Cholalic  acid  crystallizes  partly  with  one  molecule  of  water,  in 
rhombic  jalates  or  prisms,  and  partly  in  larger  rhombic  tetrahedra 
or  octahedra  with  1  mol.  of  alcohol  of  crystallization  (Mtlius). 
These  crystals  become  quickly  opaque  and  porcelain-white  in  the 
air.  They  are  quite  insoluble  in  water  (in  4000  parts  cold  and  750 
parts  boiling),  rather  soluble  in  alcohol,  but  soluble  with  difficulty 
in  ether.  The  amorphous  cholalic  acid  is  less  insoluble.  The 
solutions  have  a  sweetish-bitter  taste.  The  crystals  lose  their 
alcohol  of  crystallization  only  after  a  lengthy  heating  to  100-120°  C. 
The  acid  free  from  water  and  alcohol  melts  at  +  195 °C. 

The  alkali  salts  are  readily  soluble  in  water,  but  when  treated 
with  a  concentrated  caustic  or  carbonated  alkali  solution  may  be 
separated  as  an  oily  mass  which  becomes  crystalline  on  cooling. 
The  alkali  salts  are  not  readily  soluble  in  alcohol,  and  on  the 
evaporation  of  the  alcohol  they  may  crystallize.  The  specific 
rotary  power  of  the  sodium  salt  is  («)D  =  +  31.4°.  The  watery 
solution  of  the  alkali  salts,  when  not  too  dilute,  is  precipitated 
immediately  or  after  some  time  by  sugar  of  lead  or  by  barium 
chloride.  The  barium  salt  crystallizes  in  fine,  silky  needles, 
and  it  is  rather  insoluble  in  cold,  but  somewhat  easily  soluble  in 
warm  water.  The  barium  salt,  as  well  as  the  lead  salt  which  is  in- 
soluble in  water,  is  soluble  in  warm  alcohol. 

To  prepare  cholalic  acid  we  boil  ox-bile  for  18-36  hours' 
with  strong  caustic  alkali,  or,  better,  with  as  much  barium  hydrate 
as  the  boiling  liquid  will  dissolve.  During  the  boiling  add  when 
necessary  more  barium  hydrate.  The  boiling-hot  liquid  is  strained 
and  concentrated  until  a  crystalline  mass  separates  in  large  quantity. 
This  mass  is  separated  from  the  mother-liquor  and  strongly  pressed 
and  recrystallized  a  few  times  from  boiling  water.  The  recrystal- 
lized  baiium  salt  is  now  dissolved,  and  the  solution  decomposed  by 
hydrochloric  acid.  The  acid  which  separates  is  dissolved  in  boiling 
alcohol,  and  the  acid  generally  separates  as  crystals  immediately  on 
cooling.  By  recrystallization  from  ethyl  alcohol  and  finally  from 
methyl  alcohol  the  acid  may  be  readily  obtained  in  pure  white  crys- 
tals the  size  of  a  pea. 

Choleic  Acid,  C25H42O4,  is  another  cholalic  acid  named  by 
Latschinoff,  which  is  obtained  from  ox-bile  with  ordinary 
cholalic  acid,  though  in  very  small  amounts  (hardly  ^  the  quan- 
tity of  the   latter).     The   barium   salt   of   this    cholalic    acid    is 


150  PHY8I0L0OICAL   CHEMISTRY. 

more  readily  soluble  than  the  barium  salt  of  the  ordinary  cholalic 
acid.  Choleic  acid  yields  on  oxidation,  first,  dehydroclioleic  acidy 
C25H38O4,  and  then  cholanic  acid,  C25H3g08+  ^  HgO  (Latschinoff). 

Fellic  Acid,  CgsHioO^,  is  a  cholalic  acid,  so  called  by  Schot- 
TEN",  and  which  he  obtained  from  human  bile,  along  with  the  ordi- 
narj'  acid.  This  acid  is  crystalline,  is  insoluble  in  water,  and  yields 
barium  and  magnesium  salts  which  are  very  insoluble.  It  does 
not  give  Pettenkofer's  reaction  easily  and  gives  a  more  reddish- 
blue  color. 

The  hyo-glycocholic  and  the  cheno-taurocholic  as  well  as  the 
glycocholic  acid  of  the  bile  of  rodents  yield  corresponding  cholalic 
acids. 

On  boiling  cholalic  acids  with  acids,  by  putrefaction  in  the 
intestines,  or  by  heating,  they  lose  water  and  are  converted  into  an 
anhydride,  the  so-called  dy  sly  sin.  The  dyslysin,  Cg^HaeOs,  corre- 
sponding to  ordinary  cholalic  acid,  and  which  occurs  in  faeces, 
is  amorphous,  insoluble  in  water  and  alkalies.  Choloidic  acid  is 
called  the  first  anhydride,  or  an  intermediate  product  in  the  forma- 
tion of  dyslysin.  According  to  Hoppe-Seyler,  choloidic  acid 
is  perhaps  only  a  mixture  of  cliolalic  acid  and  dyslysin.  On  boiling 
dyslysin  with  caustic  alkali  it  is  reconverted  into  the  corresponding 
cholalic  acid. 

Glycocoll,  O2H5NO2 ,  or  amido-acetic  acid,  NHg.CHg.COOH,  also 
called  glycine,  or  sugar  of  gelatine,  has  been  found  in  the  muscles 
of  pecten  irradiajis,  but  it  is  of  special  interest  as  a  decomposi- 
tion product  of  certain  protein  substances — gelatine  and  spongin 
— as  also  of  hippuric  acid  or  glycocholic  acid  on  splitting  them  by 
boiling  with  acids. 

Glycocoll  forms  colorless,  often  large,  hard  rhombic  crystals  or 
four-sided  prisms.  The  crysttds  taste  sweet  and  dissolve  easily  in 
cold  (4.3  parts)  water.  They  are  insoluble  in  alcohol  and  ether; 
in  warm  spirits  of  wine  they  dissolve,  but  with  difficulty.  Glycocoll 
combines  with  acids  and  bases.  Under  the  last-mentioned  combi- 
nations we  must  mention  those  with  copper  and  silver.  Glycocoll 
dissolves  copper  hydroxide  in  alkaline  liquids,  but  does  not 
reduce  it  at  the  boiling  temperature.  A  boiling-hot  solution  of 
glycocoll  dissolves  freshly-precipitated  copper  hydroxide,  forming  a 
blue  liquid  from  which  dark-blue  needles  crystallize  on  cooling,  if 


TBE  LIVER.  151 

the  liquid  is  sufficiently  concentrated.     The  combination  of  gly- 
cocoU  with  HCl  is  soluble  in  water  and  alcohol. 

Glycocoll  is  best  prepared  from  hippuric  acid  by  ooiling  it  10- 
12  hours  with  4  parts  of  dilute  sulphuric  acid,  1:6.  After  cooling 
separate  the  benzoic  acid,  concentrate  the  filtrate,  remove  the  re- 
mainder of  the  benzoic  acid  by  shaking  with  ether,  remove  the  sul- 
phuric acid  by  BaCOg,  and  evaporate  the  filtrate  to  crystallization. 

Taurin,  C2H7NSO3,  or  amido-ethylsulphonic  acid,  NH2.C2H4. 
SO5OH.  This  body  is  well  known  as  a  splitting  product  of 
taurocholic  acid,  and  may  occur  in  small  quantities  in  the  contents 
of  the  intestines.  It  has  also  been  found  in  the  lungs  and  kidneys 
of  oxen  and  in  the  blood  and  muscles  of  cold-blooded  animals. 

Taurin  crystallizes  in  colorless,  often  in  large,  shining,  4-6  sided 
prisms.  It  dissolves  in  15-16  parts  of  water  at  ordinary  tempera- 
tures, but  rather  more  easily  in  warm  water.  It  is  insoluble  in  abso- 
lute alcohol  and  ether;  in  cold  sj)irits  of  wine  it  dissolves  slightly, 
but  more  when  warm.  Taurin  yields  acetic  and  sulphurous 
acids,  but  no  alkali  sulphides,  on  boiling  with  strong  caustic  alkali. 
The  amount  of  sulphur  can  be  determined  as  sulphuric  acid  after 
fusing  with  saltpetre  and  soda.  Taurin  combines  with  metallic  ox- 
ides. The  combination  with  mercuric  oxide  is  white,  insoluble, 
and  is  formed  wlien  a  solution  of  taurin  is  boiled  with  freshly-pre- 
cipitated mercuric  oxide  (J.  Lang).  This  combination  may  be 
used  in  detecting  the  presence  of  taurin.  Taurin  is  not  precipi- 
tated by  metallic  salts. 

The  preparation  of  taurin  from  bile  is  very  simple.  The  bile  is 
boiled  a  few  hours  with  hydroghloric  acid.  The  filtrate  from  the 
dyslysin  and  choloidic  acid  is  concentrated  well  in  the  water-bath, 
and  filtered  so  as  to  remove  the  common  salt  and  other  substances 
which  have  separated.  Then  evaporate  to  dryness,  and  treat  the 
residue  with  strong  alcohol,  which  dissolves  the  hydrochlorate  of 
glycocoll,  while  the  taurin  remains.  (The  alcoholic  solution  of 
hydrochlorate  of  glj'cocoU  may  be  used  in  the  preparation  of  gly- 
cocoll by  evaporating  the  alcohol  and  dissolving  the  residue  in^ 
water,  decomposing  the  solution  with  lead  hydroxide,  filtering,, 
and  freeing  the  solution  from  lead  by  H^vS,  and  strongly  concen- 
trating this  filtrate.  The  crystals  which  separate  are  dissolved  and 
decolorized  by  animal  charcoal,  and  the  solution  evaporated  to  crys- 
tallization.) The  above-obtained  residue  containing  the  taurin  is 
dissolved  in  as  little  water  as  possible,  filtered  warm,  and  treated 


152  PHT8T0L0GICAL   CHEMI8TBT. 

with  an  excess  of  alcohol.  The  crystalline  precipitate  which  im- 
mediately forms  is  filtered  as  soon  as  possible,  and  the  taurin  now 
separates,  on  cooling,  into  very  long  needles  or  prisms.  These 
crystals  may  be  purified  by  recrystallization  from  a  little  warm  water. 

Though  the  taurin  shows  no  positive  reactions,  it  is  chiefly 
identified  by  its  crystalline  form,  by  its  solubility  in  water  and  in- 
solubility in  alcohol,  by  its  combination  with  mercuric  oxide,  by  its 
non-precipitability  by  metallic  salts,  and  above  all  by  its  containing 
sulphur. 

The  Detection"  of  Bile-acids  iisr  Animal  Fluids.  To 
obtain  the  bile-acids  pure  so  that  Pettbnkofee's  test  can  be  ap- 
plied to  them,  the  albumins  and  fat  must  first  be  removed.  The 
albumin  is  removed  by  making  the  liquid  first  neutral  and  then 
adding  a  great  excess  of  alcohol,  so  that  the  mixture  contains  at  least 
85  vols,  per  cent  of  water-free  alcohol.  Now  filter,  extract  the  pre- 
cipitated albumin  with  fresh  alcohol,  unite  all  filtrates,  distil  the 
alcohol,  and  evaporate  to  dryness.  The  residue  is  completely  ex- 
hausted with  strong  alcohol,  filtered,  and  the  alcohol  entirely  evapo- 
rated from  the  filtrate.  The  new  residue  is  dissolved  in  water,  and 
ffltered  if  necessary,  and  the  solution  precipitated  by  basic  lead 
acetate  and  ammonia.  The  washed  precipitate  is  dissolved  in  boiling 
alcohol,  filtered  while  warm,  and  a  few  drops  of  soda  solution  added. 
Then  evaporate  to  dryness,  extract  the  residue  with  absolute  alcohol, 
filter,  and  add  an  excess  of  ether.  The  precipitate  now  formed  may 
be  used  for  Pettenkofer's  test.  It  is  not  necessary  to  wait  for  a 
crystallization;  but  one  must  not  consider  the  crystals  which  form 
in  the  liquid  as  being  positively-crystallized  bile.  It  is  also  possible 
for  needles  of  alkali  acetate  tobe  formed.  For  the  detection  of  bile- 
acids  in  urine  see  Chapter  XIV. 

Bile-pigments.  The  bile-coloring  matters  known  thus  far  are 
relatively  numerous,  and  in  all  probability  there  are  still  more. 
Most  of  the  known  bile-pigments  are  not  found  in  the  normal  bile, 
but  occur  either  in  post-mortem  bile  or,  principally,  in  the  bile  con- 
crements.  The  pigments  which  occur  under  physiological  condi- 
tions are  the  reddish-yellow  hiliruhin,  the  green  hiliverdin,  and  some- 
times there  is  also  observed  in  fresh  human  bile  a  pigment  closely 
related  to  Jiydrohilirubin.  The  pigments  found  in  gall-stones  are 
(besides  the  bilirubin  and  biliverdi^i)  bilifuscin,  biliprasin, 
bilihumin,  hilicyanin  (and  choletelin  P).  Besides  these,  others  have 
been  observed  in  human  and  animal  bile.  The  two  above-mentioned 
physiological  pigments,  bilirubin  and  biliverdin,  are  those  which 
serve  to  give  the   golden-yellow   or  orange-yellow  or  sometimes 


THE  LIVER.  153 

gi-eeuish  color  to  the  bile,  or  when,  as  is  most  frequently  the  case  in 
ox-bile,  the  two  pigments  are  present  in  the  bile  at  the  same  time, 
producing  the  different  shades  between  reddish  brown  and  green. 

Bilirubin.  This  pigment,  according  to  the  common  accepta- 
tion, has  the  formula  CisHigNgOs  (Maly)  and  is  designated  by  the 
names  cholepyrrhin,  biliph.^in,  bilifulyix  and  h^matoidin". 
It  occurs  chiefly  in  the  gall-stones  as  bilirubin-calcium.  It  is  further 
found  in  the  bile,  especially  in  man  and  carnivora  ;  sometimes, 
however,  the  latter  when  fasting  or  in  a  starving  condition  may 
have  a  green  bile  in  the  gall-bladder.  It  occurs  also  in  the  contents 
of  the  small  intestines,  in  blood-serum  of  the  horse,  in  old  blood 
extravasations  (as  hsematoidin),  and  in  the  urine  and  the  yellow- 
colored  tissue  in  icterus.  The  bilirubin  is  in  all  probability  a  forma- 
tion from  the  haematin  which  it  closely  resembles.  It  is  converted 
into  hydrobilirubin,  C32H40N4O7  (Maly),  by  hydrogen  in  a  nascent 
state.  It  is  claimed  by  several  investigators  to  be  identical  with  the 
urinary  pigment  urobilin,  as  well  as  with  stercohiUn  (Masius  and 
Vanlair),  which  is  found  in  the  contents  of  the  intestines.  There 
is  no  doubt  that  a  great  similarity  exists  between  these  pigments, 
but  their  identity  is  emphatically  denied  by  MAcMuxif.  On  oxida- 
tion bilirubin  yields  biliverdin  and  other  coloring  matters  (see  below). 

Bilirubin  is  partly  amorphous  and  partly  crystalline.  The 
amorphous  bilirubin  is  a  reddish-yellow  powder  of  nearly  the  same 
color  as  amorphous  antimony  sulphide;  the  crystalline  bilirubin  has 
nearly  the  same  color  as  crystallized  chromic  acid.  The  crystals, 
which  can  easily  be  obtained  by  allowing  a  solution  of  bilirubin  in 
chloroform  to  spontaneously  evaporate,  are  reddish-yellow,  rhombic 
plates,  whose  obtuse  angles  are  often  rounded. 

Bilirubin  is  insoluble  in  water,  slightly  soluble  in  ether,  some- 
what more  soluble  in  alcohol,  easily  soluble  in  chloroform,  especial- 
ly in  the  warmth,  and  less  soluble  in  benzol,  carbon  disulphide,  amyl 
alcohol,  fatty  oils,  and  glycerin.  Its  solutions  show  no  absorption- 
bands,  but  only  a  continuous  absorption  from  the  red  to  the  violet 
end  of  the  spectrum,  and  they  have,  even  on  diluting  greatly, 
(1:500000)  a  decided  green  color.  The  combinations  of  bilirubin 
with  alkalies  are  insoluble  in  chloroform,  and  bilirubin  may  be 
separated  from  its  solution  in  chloroform  by  shaking  with  dilate 
caustic  alkali  (differing  from  lutein).     Solutions  of  bilirubin-alkali 


154  PHYSIOLOGICAL   CHEMISTRY. 

in  water  are  precipitated  by  the  soluble  salts  of  the  alkaline  earths 
and  also  by  metallic  salts. 

If  an  alkaline  solution  of  bilirubin  be  allowed  to  stand  in  contact 
with  the  air,  it  gradually  absorbs  oxygen  and  green  biliverdin  is 
formed.  Biliverdin  is  also  formed  from  bilirubin  by  oxidation  under 
other  conditions.  A  green  coloring  matter  similar  in  appearance  is 
formed  by  the  action  of  other  reagents  such  as  CI,  Br,  and  I.  In  these 
cases  it  does  not  seem  to  be  biliverdin,  but  a  substitution  product  of 
bilirubin  (Thijdichum,  Malt)  which  is  obtained. 

Gmelin's  Reaction  for  Bile-pigments.  If  we  carefully  pour  under 
a  solution  of  bilirubin-alkali  in  water  nitric  acid  containing  some 
nitrous  acid,  we  obtain  a  series  of  colored  layers  at  the  juncture  of 
the  two  liquids,  in  the  following  order  from  above  downwards: 
green,  blue,  viplet,  red,  and  reddish  yellow.  This  color  reaction, 
Gmelin's  test,  is  very  delicate  and  serves  to  detect  the  presence  of 
one  part  bilirubin,  in  80,000  parts  liquid.  The  green  ring  must 
never  be  absent;  and  also  the  reddish  violet  must  be  present  at  the 
same  time,  otherwise  the  reaction  may  be  confused  with  that  for 
lutein,  which  gives  a  blue  or  greenish  ring.  The  nitric  acid  must 
not  contain  too  much  nitrous  acid,  for  then  the  reaction  takes  place 
too  quickly  and  it  does  not  become  typical.  Alcohol  must  not  be 
present  in  the  liquid,  because,  as  is  well  known,  it  gives  a  play  of 
colors,  in  green  or  blue,  with  the  acid. 

Huppert's  Reaction.  If  a  solution  of  bilirubin-alkali  is  treated 
with  milk  of  lime  or  with  calcium  chloride  and  ammonia, a  precipi- 
tate is  produced  consisting  of  bilirubin-calcium.  If  this  moist  pre- 
cipitate, which  has  been  washed  with  water,  is  placed  in  a  test- 
tube  and  the  tube  half  filled  with  alcohol  which  has  been  acidified 
with  sulphuric  acid,  and  heated  to  boiling  for^some  time,  the  liquid 
becomes  emerald-green  or  bluish  green  in  color.  This  reaction  is  a 
good  and  easily-performed  test  for  bile-pigments. 

In  regard  to  the  modifications  of  Gmelin's  test  and  certain 
other  reactions  for  bile-pigments,  see  Chapter  XIV  (Urine). 

That  the  characteristic  play  of  colors  in  Gmelitst's  test  is  the 
result  of  an  oxidation  is  generally  admitted.  The  first  oxidation 
step  is  the  green  biliverdin.  Then  follows  a  blue  coloring  matter 
which  Heiksius  and  Campbell  call  bilicyanin  and  Stokvis  calls 
cholecyanin,  and  which  shows  a  characteristic  absorption-spectrum. 


s 


THE  LIVER.  %  156 


The  neutral  solutions  of  these  coloring  matters  are, ja^c^rding  to 
Stokvis,  bluish  green  or  steel-blue  with  a  beautiful  blae  fluores- 
cence. The  alkaline  solutions  are  green  and  have  i|d  marked 
fluorescence.  The  neutral  and  alkaline  solutions  show  thre^  ab- 
sorption-bands, one  sharp  and  dark  in  the  red  between  C  and  D, 
nearer  to  C ;  a  second,  less  defined,  covering  D;  and  a  third,  form- 
ing only  a  faint  shadow,  in  the  green,  exactly  in  the  middle, 
between  D  and  E.  The  strongly-acid  solutions  are  violet-blue  and 
show  two  baTids,  described  by  Jaffe,  between  the  lines  C  and  E, 
separated  from  each  other  by  a  narrow  space  near  D.  The  next 
oxidation  step  after  these  blue  coloring  matters  gives  a  red  pig- 
ment, and  lastly  a  yellowish-brown  pigment,  called  cholefelin  by 
Malt,  which  shows  no  absorption-spectrum. 

Bilirubin  is  best  prepared  from  gall-stones  of  oxen,  these  con- 
cretions being  very  rich  in  bilirubin-ealcium.  The  finely-powdered 
concrement  is  first  exhausted  with  etber  and  then  with  boiling 
water,  so  as  to  remove  the  cholesterin  and  bile-acids.  The 
powder  is  then  treated  with  hydrochloric  acid,  which  sets  free  the 
pigment.  Wash  thoroughly  with  water  and  alcohol,  dry,  and 
extract  continuously  with  boiling  chloroform.  After  distilling  the 
chloroform  from  the  solution,  treat  tlie  powdered  residue  with 
absolute  alcohol  to  remove  the  bilifuscin  ;  dissolve  the  remaining 
bilirubin  in  a  little  chloroform  ;  precipitate  it  from  this  solution  by 
alcohol,  and  do  this  several  times  if  necessary.  The  bilirubin  is 
finally  dissolved  in  boiling  chloroform  and  allowed  to  crystallize  on 
cooling.  The  quantitative  estimation  of  bilirubin  may  be  made  by 
the  spectro-photometrical  method,  according  to  the  steps  suggested 
for  the  blood-coloring  matters. 

Biliverdin,  CgHgXOj.  This  body,  which  is  formed  by  the  oxida- 
tion of  bilirubin,  occurs  in  the  bile  of  many  animals,  in  vomited 
matter,  in  the  placenta  of  the  bitch  (?),  in  the  shells  of  birds'  eggs, 
in  the  urine  in  icterus,  and  sometimes  in  gall-stones,  although  in 
very  small  quantities. 

Biliverdin  is  amorphous,  or  at  least  it  has  not  been  obtained  in 
well-defined  crystals.  It  is  insoluble  in  water,  ether,  and  chloro- 
form (this  is  true  at  least  for  the  artificially-prepared  biliverdin, 
while  the  green  pigment  of  ox-bile  is  soluble  in  chloroform,  accord- 
ing to  Mac^Iuxx),  but  is  soluble  in  alcohol  or  glacial  acetic 
acid,  showing  a  beautiful  green  color.  It  is  dissolved  by  alkalies 
giving  a  brownish-green  color,  and  this  solution  is  precipitated  by 


156  PHYSIOLOGICAL   CHEMISTBY. 

acids,  as  well  as  by  calcium,  barium,  and  lead-salts.  Biliverdin 
gives  Huppekt's  and  GMELii^f's  reactions,  commencing  with  the 
blue  color.  It  is  converted  into  hydrobilirubin  by  nascent  hydro- 
gen. On  allowing  the  green  bile  to  stand,  also  by  the  action  of 
ammonium  sulphide,  the  biliverdin  may  be  reduced  to  bilirubin 
(Haycraft  and  Scofield). 

Biliverdin  is  most  simply  prepared  by  allowing  a  thin  layer  of 
an  alkaline  solution  of  bilirubin  to  stand  exj)osed  to  the  air  in  a 
dish  until  the  color  is  brownish  green.  The  solution  is  then  pre- 
cipitated by  hydrochloric  acid,  the  j)recipitate  washed  with  water 
until  no  HCl  reaction  is  obtained,  then  dissolved  in  alcohol  and 
the  pigment  again  separated  by  the  addition  of  water.  Any  biliru- 
bin present  may  be  removed  by  means  of  chloroform. 

Bilifuscin,  so  named  by  Stadeler,  is  an  amorphous  brown  pigment, 
soluble  in  alcohol  and  alkalies,  nearly  insoluble  in  water  and  ether,  and 
soluble  with  great  diflficulty  in  chloroform  (when  bilirubin  is  not  present  at 
the  same  lime).  It  is  found  in  post-mortem  bile  and  gall-stones.  BUiprasin 
is  a  green  pigment  prepared  by  Stadeler  from  gall-stones,  which  perhaps  is 
only  a  mixture  of  biliverdin  and  bilirubin.  Bilihumin  is  the  name  given  by 
Stadeler  to  that  brownish  amorphous  residue  which  is  left  after  extracting 
gall-stones  with  chloroform,  alcohol,  and  ether.  It  does  not  give  Gmelin's 
test.  Bilicyanin  is  also  found  in  human  gall-stones  (Heinsitjs  and  Camp- 
bell). Cholo  limmatin,  so  called  by  MacMunn,  is  a  pigment  often  occurring 
in  sheep-  and  ox-bile  and  characterized  by  four  absorption-bands,  and  which 
is  formed  from  haematin  by  the  action  of  sodium  amalgam.  In  the  dried  con- 
dition, obtained  by  the  evaporation  of  the  chloroform  solution,  it  is  green,  and 
in  alcoholic  solution  olive-brown. 

Gmelin's  and  Huppert's  reactions  are  generally  used  to  detect 
the  presence  of  bile-pigments  in  animal  fluids  or  tissues.  The  first, 
as  a  rule,  can  be  laerformed  directly,  and  the  presence  of  albumin 
does  not  interfere  with  it,  but,  on  the  contrary,  it  brings  out  the 
play  of  colors  more  strikingly.  If  blood-coloring  matters  are  present 
at  the  same  time,  the  bile-coloring  matters  are  first  precipitated  by 
the  addition  of  sodium  phosphate  and  milk  of  lime.  This  precipi- 
tate containing  the  bile-pigments  may  be  used  directly  in  Huppert's 
reaction,  or  may  be  treated  with  water  and  some  hydrochloric  acid, 
and  then  shaken  with  chloroform  free  from  alcohol,  and  this 
chloroform  solution  used  in  testing  for  the  bile-pigments. 

Besides  the  bile-acids  and  bile-pigments  we  also  have  in  the 
bile  cholesterin,  lecithin,  palmitin,  stearin,  olein,  and  soaps  of  the 
corresponding  fatty  acids.  In  some  animals  the  bile  contains  a 
diastatic  enzyme.  Gholin  and  glijcero-flios'plioric  acid,  when 
they  are  present,  may  be  considered  as  decomposition  products  of 
lecithin.  TJrea  occurs,  though  only  as  traces,  as  a  physiological 
constituent  of  human,  ox,  and  dog  bile.     The  mineral  constituents 


THE  LIVER.  157 

of  the  bile  are,  besides  the  alkalies,  to  which  the  bile  acids  are 
united,  sodium  and  potassium  chloride,  calcium  and  magnesium 
phosphate,  and  iron — 0.04-0.11  p.  m.  in  human  bile,  chiefly  com- 
bined with  phosphoric  acid  (Young).  Traces  of  copper  are  habitu- 
ally  present,  and  traces  of  zinc  are  often  found.  Sulphates  are 
entirely  absent  or  only  occur  in  very  small  amounts. 

Quantitative  Composition  of  the  Bile.  Complete  analyses  of 
human  bile  have  been  made  by  Hoppe-Seyler  and  his  pupils. 
The  bile  was  removed  as  fresh  as  possible  from  the  gall-bladder  of 
cadavers  whose  livers  showed  no  remarkable  change.  The  follow- 
ing figures  of  SocOLOFF  are  the  average  of  six  analyses,  and  those 
of  Hoppe-Seyler  of  five  analyses.  The  relationship  between  the 
glycocholate  and  taurocholate  was  found  by  fusing  the  precipitate 
consisting  of  biliary  alkalies  obtained  by  ether  from  the  alcoholic 
extract  with  saltpetre  and  soda.  On  determining  the  amount  of 
sulphur  in  the  fused  mass  the  taurocholic  acid  can  be  calculated 
from  this.  100  parts  BaSO^  correspond  to  220.86  parts  taurocholic 
acid.     The  figures  are  parts  per  1000. 

Trifanowski.  Socolofp.  Hoppe-Setler. 
I.         II. 

Mucin 24.8    13.0)  „„  go  ^^-^ 

Remaining  bodies  iusol.  iu  alcohol. .     4.5    14.6  i  1.4 

Taurocholate 7.5    19.2  15.67  8.7 

Glycocholate 21.0      4  4  49  04  30.3 

Soaps 8,1     16.3  14.60  13.9 

Cholesleriu 2  5      3.3  3.5 

Lecithin )    f.  „      0.2  3.3 

Fat j    ^-^      3.6  ....  7.3 

Ferric  phosphate 0. 166 

Older  and  less  complete  analyses  of  human  bile  have  been  made 
by  Frerichs  and  v.  Gorup-Besanez.  The  bile  analyzed  by  them 
was  from  perfectly  healthy  persons  who  had  been  executed  or  acci- 
dentally killed.  The  two  analyses  of  Frerichs  ai-e,  respectively, 
of  (I)  an  18-year-old  and  "(11)  a  32-year-old  male.  Tlie  analyses  of 
V.  Gorup-Besanez  are  of  (I)  a  man  of  49  and  (II)  a  woman  of  29. 
The  results  are,  as  usual,  in  parts  per  1000. 

Frerichs.  v.  Gobup-Bksankz. 

I.  II.  I.  II. 

Water 860.0  859.2  822.7  898.1 

Solids 140.0  140.8  177.3  101.9 

Biliary  salts 72.2  91.4  107.9  56.5 

Mucus  and  pigments 26.6  29.8  22.1  14.5 

Cholesterin 1.6  2.6" 

Fat 3.2  9.2 


I 


47.3         30.9 


Inorganic  substances 6.5  7.7  10.8  6.3 


158  PETSIOLOQIGAL   CHEMISTRY. 

The  bile  of  the  gall-bladder  is,  as  above  stated,  richer  in  solids 
than  the  bile  of  the  liver.  Human  bile  obtained  by  means  of  a 
fistula  contained  22.4-22.8  p.  m.  solids,  according  to  Jacobsbn, 
who  determined  the  mineral  substances  in  the  same  bile  and 
found  the  following,  calculated  from  the  dry  residue:  KCl  12.85, 
NaCl  245.1,  NasPO^  59.8,  G'a^{'PO^)^  3  6.7,  and  NajCOa  41.8  p.  m. 

The  relationship  between  the  amounts  of  glycocholates  and 
taurocholates  in  the  human  bile  seems  to  be  quite  variable. 
According  to  the  analyses  and  observations  of  the  majority  of  in- 
vestigators, the  human  bile  is,  in  most  cases,  relatively  richer  in 
glycocholic  acid  and  correspondingly  poor  in  taurocholic  acid. 

In  animals  the  relative  proportion  of  the  two  acids  varies  very 
much.  It  has  been  found,  on  determining  the  amount  of  sulphur, 
that,  so  far  as  the  experiments  have  gone,  taurocholic  acid  is  the 
prevailing  acid  in  carnivorous  mammalia,  birds,  snakes,  and  fishes. 
Among  the  herbivora  sheep  and  goats  have  a  predominance  of 
taurocholic  acid  in  the  bile.  Ox-bile  sometimes  contains  tauro- 
cholic acid  in  excess,  in  other  cases  glycocholic  acid  predominates, 
and  in  a  few  cases  the  latter  occurs  almost  alone.  The  bile  of  the 
rabbit,  hare,  and  kangaroo  contains,  like  the  bile  of  the  pig,  almost 
exclusively  glycocholic  acid.  A  distinct  influence  on  the  relative 
amounts  of  the  two  bile-acids  by  different  foods  has  not  been  de- 
tected. RiTTER  claims  to  have  found  a  decrease  in  the  quantity 
of  taurocholic  acid  in  calves  when  they  pass  from  the  milk  to 
the  plant  diet. 

The  gases  of  the  bile  consist  of  a  large  quantity  of  carbon 
dioxide,  which  increases  with  the  amount  of  alkalies,  only  traces  of 
oxygen,  and  a  very  small  quantity  of  nitrogen. 

Little  is  known  in  regard  to  the  pi'operties  of  the  bile  in  dimise. '  The  quan- 
tity of  urea  is  found  to  be  considerably  increased  in  ursemia.  Leucin  and 
tyrosin  are  observed  in  acute  yellow  atrophy  of  the  liver  and  in  typhus. 
Traces  of  albumin  (without  regard  to  nucleoalbumin)  have  several  times 
been  found  in  the  human  bile.  The  so-called  pigmentary  acholia,  or  the 
secretion  of  a  bile  containing  bile-acids  but  no  bile-pigments,  has  also  been 
repeatedly  noticed.  In  all  such  cases  observed  by  Rittek  he  found  a 
fatty  degeneration  of  the  liver-cells,  in  return  for  which,  even  in  excessive 
fat  infiltration,  a  normal  bile  containing  pigments  was  secreted.  The  secre- 
tion of  a  bile  nearly  free  from  bile-acids  has  been  observed  by  Hoppe-Seylek 
in  amylaceous  degeneration  of  the  liver,  and  also  by  K.  Morner.  A  number 
of  substances,  such  as  turpentine,  salicylic  acid,  potassium  bromide  and 
iodide,  arsenic,  iron,  lead,  and  mercury  (Prevost  and  Binet),  are  eliminjited 
by  the  bile.     In  animals,  dogs,  and  especially  rabbits  it  has  been  observed 


THE  LIVER.  159 

that  the  blood-coloring  matters  pass  into  the  bile  in  poisoning  and  in  other 
cases,  caiisiug  a  destruction  of  the  blood-corpuscles  (Wertheimeb  and 
Meter,  Filehne). 

Chemical  Formation  of  the  Bile.  The  first  question  to  be 
answered  is  the  following  :  Do  the  specific  constituents  of  the  bile, 
the  bile-acids  and  bile-pigments,  originate  in  the  liver;  and  if  this 
is  the  case,  do  they  come  from  this  organ  only,  or  are  they  also 
formed  elsewhere  ? 

The  investigations  of  the  blood,  and  especially  the  comparative 
investigations  of  the  blood  of  the  portal  and  hepatic  veins  under 
normal  conditions,  have  not  given  any  answer  to  this  question.  To 
decide  this,  therefore,  it  is  necessary  to  extirpate  the  liver  of 
animals  or  isolate  it  from  the  circulation.  If  the  bile  constituents 
are  not  formed  in  the  liver  or  at  least  not  alone  in  this  organ,  but 
only  eliminated  from  the  blood,  then,  after  the  extirpation  or  re- 
moval of  the  liver  from  the  circulation,  an  accumulation  of  the  bile 
constituents  is  to  be  expected  in  the  blood  and  tissues.  If  the  bilo' 
constituents,  on  the  contrary,  are  formed  exclusively  in  the  liver, 
then  the  above  operation  naturally  would  give  no  such  result.  It 
the  choledochus  duct  is  tied,  then  the  bile  constituents  will  be 
collected  in  the  blood  or  tissues  whether  they  are  formed  in  the 
liver  or  elsewhere. 

From  these  principles  Kobner  has  tried  to  demonstrate  by  ex- 
periments on  frogs  that  the  bile-acids  are  produced  exclusively  in  the 
liver.  While  he  was  unable  to  detect  any  bile-acids  in  the  blood 
and  tissues  of  these  animals  after  extirpation  of  the  liver,  still  he 
was  able  to  discover  them  on  tying  the  choledochus  duct.  The 
investigations  of  LuDWiG  and  Fleischl  show  that  in  the  dog 
the  bile-acids  originate  in  the  liver  alone.  After  tying  the  chole- 
dochus duct  they  observed  that  the  bile  constituents  were  absorbed 
by  the  lymphatic  vessels  and  passed  into  the  blood  through  the 
thoracic  duct.  Bile-acids  could  be  detected  in  the  blood  after  such 
an  operation,  while  they  could  not  be  detected  in  the  normal  blood. 
But  when  the  choledochus  and  thoracic  ducts  were  both  tied  at  the 
same  time,  then  not  the  least  trace  of  bile-acids  could  be  detected 
in  the  blood,  while  if  they  are  also  formed  in  other  organs  and  tissues 
they  should  have  been  present.  The  general  opinion  is  that  the 
bile-acids  are  formed  only  in  the  liver;  still  there  are  investigators 


160  PHYSIOLOGICAL   CEEMI8TRT. 

who  have  other  views.  Baldi  claims  that  the  formation  of  bile- 
acids  does  not  take  place  only  in  the  liver,  but  in  the  entire 
organism,  and  he  claims  to  have  detected  bile-acids  in  the  normal, 
circulating  blood  of  different  organs. 

It  has  been  indubitably  proved  that  the  bile-pigtnents  may  be 
formed  in  other  organs  besides  the  liver,  for,  as  is  generally  ad- 
mitted, the  coloring  matter  hsematoidin,  which  occurs  in  old  blood 
extravasations,  is  identical  with  the  bile-pigment  bilirubin  (see  page 
80).  Latschenbergee,  has  also  observed  in  horses,  under  physio- 
logical conditions,  a  formation  of  bile-pigments  from  the  blood- 
coloring  matters  in  the  tissues.  Also  the  occurrence  of  bile- 
pigments  in  the  placenta  seems  to  depend  on  their  formation  in 
that  organ,  while  the  occurrence  of  small  quantities  of  bile-pigments 
in  the  blood-serum  of  certain  animals  probably  depends  on  an  ab- 
sorption of  the  same.  * 

Though  the  bile-pigments  may  be  formed  in  other  organs,  it 
still  seems  that  their  formation  under  physiological  conditions 
occurs  mainly  in  the  liver.  By  experimenting  on  pigeons  Sterk 
was  able  to  detect  bile-pigments  in  the  blood-serum  five  hours  after 
tying  the  biliary  passages  alone,  while  after  tying  all  the  vessels  of 
the  liver  and  also  the  biliary  passages  no  bile-pigments  could  be 
detected  either  in  the  blood  or  the  tissues  of  the  animal,  which  was 
killed  10-12  hours  after  the  operation.  Minkowski  and  Natjntn 
have  also  found  that  poisoning  with  arseniuretted  hydrogen  pro- 
duces a  liberal  formation  of  bile-pigments  and  the  secretion,  after  a 
short  time,  of  a  urine  rich  in  biliverdin  in  previously  healthy  geese. 
In  geese  with  extirpated  livers  this  does  not  occur.  The  great  im- 
portance of  the  liver  in  the  formation  of  bile-pigments  seems  to  be 
settled,  even  though  these  bodies  may  be  formed  also  in  other  organs. 

In  regard  to  the  materials  from  which  the  bile-acids  are  pro- 
duced, it  may  be  said  with  certainty  that  the  two  components, 
glycocoll  and  taurin,  which  are  both  nitrogenized,  are  formed 
from  the  protein  bodies.  In  regard  to  the  origin  of  the  non-nitro- 
genized  cholalic  acid,  which  was  formerly  considered  as  originat- 
ing from  the  fats,  we  know  nothing  positively. 

The  blood -coloring  matters  are  considered  as  the  mother- 
substance  of  the  bile-pigments.  If  the  identity  of  hsematoidin 
and  bilirubin  were  beyond  doubt,  then  this  view  might  be  consid- 


THE  LIVER.  161 

ered  as  proved.  Independently,  however,  of  this  identity,  which  is 
not  admitted  by  all  investigators,  the  view  that  the  bile-pigments 
are  derived  from  the  blood-coloring  matters  has  strong  arguments 
in  its  favor.  It  has  been  shown  by  several  experimenters  (lately  by 
Latschexbekger)  that  a  yellow  or  yellowish-red  coloring  matter 
can  be  formed  from  the  blood-coloring  matters  which  gives  GMELi2>f's 
test,  and  which,  though  it  may  not  form  a  complete  bile-pigment, 
is  at  least  a  step  in  its  formation  (Latschenbergee).  A  further 
proof  of  the  formation  of  the  bile-pigments  from  the  blood-color- 
ing matters  consists  in  the  fact  that  hgematin  yields  urobilin,  which 
is  identical  with  hydrobilirubin,  on  reduction  (Hoppe-Setler). 
Other  investigators  (Nexcki  and  Sieber  and  Le  Nobel)  claim 
that  the  substance  thus  obtained  is  not  true  urobilin,  but,  all  things 
considered,  it  seems  to  be  very  nearly  related. 

But  even  though  the  identity  of  urobilin  with  the  hydro- 
bilirubin obtained  by  the  reduction  of  bilirubin  is  disputed  by 
certain  investigators  (MacMunn),  still  the  substances  may  be  so 
closely  related  that  the  relationship  will  serve  as  a  proof  of  the  for- 
mation of  bilirubin  from  the  blood-coloring  matters.  Further, 
haematoporphyrin  (see  page  78)  and  bilirubin  are  isomers,  accord- 
ing to  Nexcki  and  Sieber,  and  nearly  allied.  The  formation  of 
bilirubin  from  the  blood-coloring  matters  is  shown,  according 
to  the  observations  of  several  investigators,  by  the  appearance  of 
free  hsemoglobin  in  the  plasma — by  the  destruction  of  the  red 
corpuscles  by  widely-differing  influences  (see  below)  or  by  the  in- 
jection of  hgemoglobin  solution — causing  an  increased  formation  of 
bile-pigments.  The  amount  of  pigments  in  the  bile  is  not  only 
considerably  increased  (Tarchanoff),  but  the  bile-pigments  may 
even  pass  into  the  urine  under  certain  circumstances  (icterus). 
After  the  injection  of  haemoglobin  solution  into  a  dog  either  sub- 
cutaneously  or  in  the  peritoneal  cavity,  Gorodecki  observed  in  the 
secretion  of  pigments  by  the  bile  an  increase  of  QOfo  which  lasted  for 
twenty  hours. 

If,  then,  iron-free  bilirubin  is  derived  from  the  haematin  con- 
taining iron,  then  iron  must  be  split  off.  This  process  may  be 
represented  by  the  following  formula,  according  to  Nencki  and 
Sieber, 

Cs^Hs^N.O.Fe  +  2H2O  -  Fe  -  2Ci6H,8NA, 


162  PHTSIOLOGICAL   CHEMISTRY. 

though  iu  reality  it  is  probably  more  complicated.  The  question 
in  what  form  or  combination  the  iron  is  split  off  is  of  special  inter- 
est, and  also  whether  it  is  eliminated  by  the  bile.  This  latter  does 
not  seem  to  be  the  case.  In  100  parts  of  bilirubin  which  are  elimi- 
nated by  the  bile  there  are  only  1.4-1.5  parts  iron,  according  to 
KuxKEL  ;  while  100  parts  hsematin  contain  about  9  parts  iron. 
Minkowski  and  Baseein"  have  also  found  that  the  abundant 
formation  of  bile-pigments  occurring  in  poisoning  by  arseniuretted 
hydrogen  does  not  increase  the  quantity  of  iron  in  the  bile.  The 
quantity  apparently  does  not  correspond  with  that  in  the  decom- 
posed blood-coloring  matters. 

On  the  contrary,  it  seems  as  if  the  iron,  at  least  for  a  time,  is 
retained  by  the  liver  as  a  pigment  rich  in  iron.  Such  a  pigment 
containing  iron,  which  was  formed  by  the  decomposition  of 
haemoglobin,  was  observed  by  Naunyn  and  Minkowski  in  the 
livers  of  birds,  in  arseniuretted  hydrogen  icterus.  Latschbn- 
BERGER  claims  that  a  yellow  or  yellowish  red  pigment, "  choleglobiji," 
is  derived  from  the  blood-coloring  matters,  and  acts  as  a  step  in  the 
formation  of  the  bile-pigments;  and  besides  this  he  mentions  an- 
other body  consisting  of  dark  grains  and  containing  iron,  which  he 
designates  as  melanin.  Neumann  has  observed  in  blood  extrav- 
asations, besides  hsematoidin,  a  pigment  containing  iron,  for  which 
he  has  proposed  the  name  licBmatosiderin. 

An  absorption  of  bile  from  the  liver  by  the  lymphatic  vessels 
and  the  passage  of  the  bile-constituents  into  the  blood  and  urine 
occurs  in  retarded  discharge  of  the  bile,  and  usually  in  the  differ- 
ent forms  of  hepatogenic  icterus.  But  bile-pigments  may  also  pass 
into  the  urine  under  other  circumstances,  especially  in  animals 
wiiere  a  solution  or  destruction  of  the  red  blood-corpuscles  takes 
place  through  injection  of  water  or  a  solution  of  biliary  salts,  through 
poisoning  by  ether,  chloroform,  arseniuretted  hydrogen,  or  toluylen- 
diamin;  and  in  other  cases.  This  occurs  also  in  man  in  grave 
infectious  diseases.  We  have  therefore  a  second  form  of  icterus, 
in  which  the  blood-coloring  matters  are  transformed  into  bile- 
pigments  elsewhere  than  in  the  liver,  blood,  and  tissues — a 
}i(Bmato genie,  chemical,  or  anhepatogenic  icterus.  Only  bile-pig- 
ments occur  in  the  urine  in  these  cases,  while  in  hepatogenic 
icterus  the  urine  contains  the  bile-pigments  and  bile-acids  at  the 


THE  LIVER.  163 

same  time  (Leyden).  This  distinction,  however,  cannot  be  main- 
tained. It  is  certainly  true  that  the  presence  of  more  than  traces 
of  bile-acids  in  the  urine  indicates  the  existence  of  hepatogenic 
icterus;  but  cases  of  absorption  icterus  undoubtedly  occur  in  which 
no  bile-acids  can  be  detected  in  the  urine. 

It  has  been  clearly  demonstrated  by  the  above-mentioned  obser- 
vations of  Minkowski  and  Nauxyn  on  geese  with  extirpated 
livers  that  the  bile-pigments  are  formed  in  the  liver  in  arseni- 
uretted  hydrogen  icterus.  It  has  also  been  demonstrated  by  Stadel- 
MANN  and  Afanassiew  that  the  icterus,  after  poisoning  by  arseni- 
uretted  hydrogen  or  by  toluylendiamin,  must  be  considered  as  an 
absorption  icterus.  Perhaps  the  icterus  depends  in  these  cases 
upon  the  fact  that  the  viscosity  of  the  abundantly-secreted  bile  may 
form  a  check  to  its  outflow,  which  counteracts  the  low  secretion 
pressure,  so  that  a  stowing  and  absorption  occurs  {jyolychoUc 
icterus).  It  is  also  possible  that  other  cases  of  so-called  haematogenic 
icterus  may  be  of  an  analogous  kind,  and  that  every  icterus  is 
consequently  hepatogenic.  The  occurrence  of  haematogenic  icterus 
cannot  be  considered  as  proved  beyond  doubt,  and  it  is  questioned 
by  several  recent  investigators. 

Appendix  to  the  Bile.    Bile  Concretions. 

The  concrements  which  occur  in  the  gall-bladder  vary  consider- 
ably in  size,  form,  and  number,  and  are  of  three  kinds,  depending 
upon  the  kind  and  nature  of  the  bodies  forming  their  chief  mass. 
One  group  of  gall-stones  contains  lime-pigment  as  chief  constituent, 
the  other  cholesterin,  and  the  third  calcium  carbonate  and  phos- 
phate. The  concrements  of  the  last-mentioned  group  occur  very 
seldom  in  man.  The  so-called  cholesterin  stones  are  those  which 
occur  most  frequently  in  man,  while  the  lime-pigment  stones  are 
not  found  very  often  in  man,  but  often  in  oxen. 

The  pigment-stones  are  generally  not  large  in  man,  but  in  oxen 
and  pigs  they  are  sometimes  found  the  size  of  a  walnut  or  even 
larger.  In  most  cases  they  consist  chiefly  of  bilirubin-calcium  with 
little  or  no  biliverdin.  Sometimes  also  small  black  or  greenish 
black,  metallic-looking  stones  are  found,  which  consist  chiefly  of 
hilifuscin  along  with  biliverdin.     Iron  and  copper  seem  to  be  reg- 


164  PHTSIOLOOICAL   CUEMI8TBT. 

ular  constituents  of  pigment-stones.  Manganese  and  zinc  have 
also  been  found  a  few  times.  The  pigment-stones  are  generally 
heavier  than  water. 

The  cholesterin-stones,  whose  size,  form,  color,  and  structure 
may  vary  greatly,  are  often  lighter  than  water.  The  fractured  sur- 
face is  radiated,  crystalline,  and  frequently  shows  crystalline,  con- 
centric layers.  The  cleavage  fracture  is  waxy  in  appearance,  and 
the  fracturod  surface  when  rubbed  by  the  nail  also  becomes  like 
wax.  By  rubbing  against  each  other  in  the  gall-bladder  they  often 
become  faceted  or  take  other  remarkable  shapes.  Their  surface  is 
sometimes  nearly  white  and  waxlike,  but  generally  their  color  is 
variable.  The  quantity  of  cholestrin  in  the  stones  varies  from  643 
to  981  p.  m.  (Rittbe).  The  cholesterin-stones  also  sometimes  con- 
tain variable  amounts  of  lime-pigments  which  give  thfem  a  very 
changeable  appearance. 

Cholesterin,  CgsH^iO,  or,  according  to  Eeinitzer,  CgrHiyO, 
Cholesterin  is  generally  considered  as  a  monatomic  alcohol  of  the 
formula  CaoHig.OH.  It  yields  a  colored  hydrocarbon  {cholesteriline 
or  cholesterone),  of  the  formula  CgsHis,  with  sulphuric  acid,  and 
this  hydrocarbon  is  claimed  by  Wetl  to  be  nearly  related  to  the 
terpene  group  It  has  also  been  claimed  that  it  is  closely  allied 
to  cholalic  acid. 

Cholesterin  occurs  in  small  amounts  in  nearly  all  animal  fluids 
and  juices.  It  occurs  only  rarely  in  the  urine,  and  then  in  very 
small  quantities.  It  is  also  found  in  the  different  tissues  and  organs — 
especially  abundant  in  the  brain  and  the  nervous  system, — further 
in  the  5'olk  of  the  egg,  in  semen,  and  in  wool-fat.  It  appears  (to- 
gether with  isocholesterin)  in  the  contents  of  the  intestines,  in 
excrements,  and  in  the  meconium.  It  occurs  pathologically  espe- 
cially in  gall-stones,  as  well  as  in  atheromatous  cysts,  in  pus,  in  tu- 
berculous masses,  old  transudations,  cystin  fluids,  excrements,  and 
tumors.  Several  kinds  of  cholesterin  seem  to  occur  in  the  plant 
world 

Cholesterin  which  crystallizes  from  warm  alcohol  on  cooling, 
and  that  which  is  present  in  old  transudations,  contains  1  mol.  of 
water  of  crystallization,  melts  at  137°  C,  and  forms  colorless,  trans- 
parent plates  whose  sides  and  angles  frequently  appear  broken  and 
whose  acute  angle  is  often  76°  30'  or  87°  30'.     In  large  quantities 


THE  LIVER.  165 

it  appears  as  a  mass  of  white  plates  which  shine  like  mother-of- 
pearl  and  have  a  greasy  feel. 

Cholesterin  is  insoluble  in  water,  dilute  acids  and  alkalies.  It  is 
neither  dissolved  nor  changed  by  boiling  caustic  alkali.  It  is  easily 
soluble  in  boiling  alcohol  and  crystallizes  on  cooling.  It  dissolves 
readily  in  ether,  chloroform,  and  benzol,  and  also  in  the  volatile  or 
fatty  oils.  It  is  dissolved  to  a  slight  extent  by  alkali  salts  of  the  bile, 
acids.  For  the  detection  of  cholesterin  we  make  use  of  its  action 
with  concentrated  sulphuric  acid,  which,  as  above  stated,  gives  a 
colored  hydrocarbon  with  this  acid. 

If  a  mixture  of  five  parts  sulphuric  acid  and  one  part  water  acts 
on  a  cholesterin  crystal,  this  crystal  will  show  colored  rings,  first  a 
bright  carmine-red  and  then  violet.  This  fact  is  made  use  of  in  the 
microscopic  detection  of  cholesterin.  Another  test,  and  one  very 
good  for  the  microscopical  detection  of  cholesterin,  consists  in  treat- 
ing the  crystal  first  with  the  above  dilute  acid  and  then  with  some 
iodine  solution.  The  crystals  will  be  gradually  colored  violet, 
bluish  green,  and  a  beautiful  blue. 

Salkowski's  Reaction.  The  cholesterin  is  dissolved  in  chloro- 
form and  then  treated  with  an  equal  volume  of  concentrated 
sulphuric  acid.  The  cholesterin  solution  becomes  first  bluish 
red,  then  gradually  more  violet-red,  while  the  sulphuric  acid  ap- 
pears dark  red  with  a  greenish  fluorescence.  If  the  chloroform 
solution  is  poured  into  a  porcelain  dish  it  becomes  violet,  then 
^reen,  and  finally  yellow. 

ScHiFP's  Reaction.  If  a  little  cholesterin  is  placed  in  a  porcelain  dish 
with  the  addition  of  a  few  drops  of  a  mixture  of  two  to  three  vols.  cone. 
h3^drochloric  acid  or  sulphuric  acid  and  one  vol.  of  a  medium  solution  of 
ferric  chloride,  and  carefully  evaporated  to  dryness  over  a  small  flame,  a  red- 
dish-violet residue  is  first  obtained  and  then  a  bluish  violet. 

If  a  small  quantity  of  cholesterin  is  evaporated  to  dryness  with  a  drop  of 
concentrated  nitric  acid,  we  obtain  a  yellow  spot  which  becomes  deep  orange- 
red  with  ammonia  or  caustic  soda  (not  a  characteristic  reaction). 

_  Isocholesterin.  This  body,  so  called  by  Schultze,  is  isomeric  with  the 
ordinar}' cholesterin  and  occurs  in  wool-fat,  and  is  therefore  found  in  abun- 
dant quantities  in  so-called  lanolin.  It  does  not  give  Salkowski's  or  Schifp's 
reactions. 

We  make  use  of  the  so-called  cholesterin-stones  in  the  prepara- 
tion of  cholesterin.  The  powder  is  first  boiled  with  water  and 
then  repeatedly  boiled  with  alcohol.  The  cholesterin  which 
on  cooling  separates  from  the  warm  filtered  solution   is  boiled  with 


166  PHYSIOLOGICAL   CHEM18TRT. 

a  solution  of  caustic  potash  in  alcohol  so  as  to  saponify  any  fat. 
After  the  evaporation  of  the  alcohol  we  extract  the  cholesterin  from 
the  residue  with  ether,  by  which  the  soaps  are  not  dissolved,  filter, 
evaporate  the  ether,  and  purify  the  cholesterin  by  recrystallization 
from  alcohol-ether.  The  cholesterin  may  be  extracted  from  tissues 
and  fluids  by  first  extracting  with  ether  and  then  purifying  as 
above. 

It  is  detected  and  determined  quantitatively  in  tissue,  etc.,  by 
this  same  method.  It  is  ordinarily  easily  detected  in  transudations 
and  pathological  formations  by  means  of  the  microscope. 


CHAPTER  VII. 
DIGESTION. 

The  purpose  of  the  digestion  is  to  separate  those  constituents 
of  the  food  which  serve  as  the  nutriment  of  the  body  from  those 
which  constitute  the  waste,  and  to  separate  each  in  such  a  form 
that  it  may  be  easily  taken  up  by  the  blood  from  the  alimentary 
canal  and  conveyed  to  its  proper  organism.  This  demands  not 
only  mechanical  but  also  chemical  action.  The  first  action  which 
essentially  depends  on  the  physical  properties  of  the  food  consists 
in  a  tearing,  cutting,  crushing,  or  grinding  of  the  food,  and  serves 
chiefly  to  convert  the  nutritive  bodies  into  a  soluble  and  easily- 
absorbed  form,  or  in  the  splitting  of  the  same  into  simpler  combi- 
nations for  use  in  the  animal  synthesis.  The  solution  of  the 
nutritive  bodies  may  take  place  in  certain  cases  by  the  aid  of  water 
alone,  but  in  most  cases  a  chemical  metamorphosis  or  splitting  is 
necessary,  and  is  effected  by  means  of  the  acids  or  alkalies,  or  by 
the  fluids  secreted  by  the  glands.  The  study  of  the  processes  of 
digestion  from  a  chemical  standpoint  must  therefore  begin  with 
the  digestive  fluids,  their  qualitative  and  quantitative  compositioji, 
as  well  as  their  action  on  the  nutriments  and  foods. 

I.  The  Salivary  Glands  and  the  Saliva. 

The  salivary  glands  are  partly  alhuminous-glands  (as  the  parotid 
in  man  and  mammalia  and  the  submaxillary  in  rabbits),  partly 
mucous-glands  (as  some  of  the  small  glands  in  the  buccal  cavity  and 
the  sublingual  and  submaxillary  glands  of  many  animals),  and 
partly  mixed  glands  (as  the  submaxillary  gland  in  man).  The 
alveoli  of  the  albumin  glands  contain  cells  which  are  rich  in 
albumin,  but  contain  no  mucin.     The  alveoli  of  the  mucin-glands 

167 


168  PHYSIOLOGICAL  CHEMISTRY. 

contain  cells  rich  in  mucin  but  poor  in  albumin,  A  cell  rich  in 
albumin  may  also  occur  in  the  submaxillary  and  sublingual  glands 
between  the  mucus-cells  and  the  membrana  propria,  which  in  a 
few  cases  akes  the  form  of  a  half-moon  (lunula,  according  to 
GiANUZZi),  and  in  other  cases  the  cells  rich  in  mucin  are  sur- 
rounded as  by  a  ring,  and  sometimes  certain  alveoli  may  be  com 
pletely  filled.  By  continuous  secretion  the  mucin-cells  seem  to 
give  up  all  their  mucin  (Ewald,  Stohe),  so  that  only  albumin-cells 
are  to  be  seen  (Heidenhain).  During  rest  the  mucin-cells  are 
re-formed.  According  to  the  analyses  of  Oidtman",  the  salivary 
glands  of  a  dog  contain  790  p.  m.  water,  200  p.  m.  organic  and  10 
p,  m.  inorganic  solids.  Among  the  solids,  in  addition  to  albumin, 
we  find,  nucleoalhumin  and  mucin,  diastatic  enzyme,  in  certain 
animals  nuclein,  extractive  bodies,  leucin,  traces  of  xanthin  bodies, 
and  mineral  substances. 

The  saliva  is  a  mixture  of  the  secretion  of  the  above-mentioned 
groups  of  glands;  therefore  it  is  proper  that  we  first  study  each  of 
the  different  secretions  by  itself,  and  then  the  mixed  saliva. 

The  submaxillary  saliva  in  man  may  be  easily  collected  by 
introducing  a  canula  into  the  Wharton's  duct. 

The  submaxillary  saliva  has  not  always  the  same  composition 
or  properties;  these  depend  essentially  upon  the  conditions  under 
which  the  secretion  takes  place.  That  is  to  say,  the  secretion  is 
partly  dependent  on  the  cerebral,  partly  on  the  sympathetic, 
nervous  system.  In  consequence  of  this  dependence  the  two  dis- 
tinct varieties  of  submaxillary  secretion  are  distinguished  as  c7iorc?a- 
and  sym2Mthetic  saliva.  A  third  kind  of  saliva,  the  so-called  para- 
lytic saliva,  is  secreted  after  poisoning  with  curara  or  after  the 
severing  of  the  glandular  nerves. 

The  difference  between  chordal  and  sympathetic  saliva  (in  dogs) 
consists  chiefly  in  their  quantitative  constitution,  namely,  the  less 
abundant  sympathetic  saliva  is  more  viscous  and  richer  in  solids, 
especially  in  mucin,  than  the  more  abundant  chordal  saliva.  The 
specific  gravity  of  the  chordal  saliva  of  the  dog  is  1.0039-1.0046  and 
contains  from  12  to  14  p.  m.  solids  (Eckhard).  The  sympathetic 
has  a  specific  gravity  of  1.0075-1.018,  with  16-28  p.  m.  solids.  The 
gases  of  the  chordal  saliva  have  been  investigated  by  Pfluger.  He 
found  0.5-0.8^  oxygen,  0.9-1^  nitrogen,  and  64.73-85.13^  carbon 


DIGESTION.  169 

dioxide — all  results  calculated  at  0°  C.  and  760  mm,  pressure.  The 
greater  part  of  the  carhon  dioxide  was  chemically  combined. 

The  two  kinds  of  submaxillary  secretion  just  named  have  not 
thus  far  been  separately  studied  in  man.  The  secretion  may  be 
excited  by  a  psychological  conception,  by  mastication,  and  by  irri- 
tating the  mucous  membrane  of  the  mouth,  especially  with  acid- 
tasting  substances.  The  submaxillary  saliva  in  man  is  ordinarily 
clear,  rather  thin,  a  little  ropy,  and  froths  easily.  Its  reaction  is 
alkaline.  The  specific  gravity  is  1.002-1.003,  and  it  contains  3.6-4.5 
p.  m.  solids.  We  find  as  organic  constituents  mucin,  traces  of 
albumin  and  diastatic  enzyme  is  absent  in  several  species  of  animals. 
The  inorganic  bodies  are  alkali  chlorides,  sodium  and  magnesium 
phosphates,  besides  bicarbonates  of  the  alkalies  and  calcium. 
Oehl  finds  0.036  p.  m.  potassium  sulphocyanide  in  this  saliva. 

The  Sublingual  Saliva.  The  secretion  of  this  saliva  is  also 
influenced  by  the  cerebral  and  the  sympathetic  nervous  system. 
The  chord al  saliva,  which  is  secreted  only  to  a  small  extent, 
contains  numerous  salivary  corpuscles,  but  is  otherwise  transparent 
and  very  ropy.  Its  reaction  is  alkaline  and  contains,  according  to 
HEiDENHAi]sr,  27.5  p.  m.  solids  (in  dogs). 

The  sublingual  secretion  in  man  has  been  investigated  by  Oehl. 
It  was  clear,  mucilaginous,  more  alkaline  than  the  submaxillary 
saliva,  and  contained  mucin,  diastatic  enzymes,  and  potassium 
sulphocyanide. 

Buccal  mucus  can  only  be  obtained  pure  from  animals  by  the 
method  of  Bidder  and  Schmidt,  which  consists  in  tying  the  exit 
to  all  the  lai-ge  salivary  glands  and  cutting  off  their  secretion  from 
the  mouth.  The  quantity  of  liquid  secreted  under  these  circum- 
stances (in  dogs)  was  so  very  small  that  the  investigators  named 
were  able  to  collect  only  2  grins,  buccal  mucus  in  the  course  of 
twenty-four  hours.  It  is  a  thick,  ropy,  sticky  liquid  containing 
mucin;  it  is  rich  in  form-elements,  above  all  in  flat  epithelium- 
cells,  mucous  cells,  and  salivary  corpuscles.  The  quantity  of  solids 
in  the  buccal  mucus  of  the  dog  is,  according  to  Bidder  and 
Schmidt,  9.98  p.  m. 

Parotid  Saliva.  The  secretion  of  this  saliva  is  also  partly  de- 
pendent on  the  cerebral  nervous  system  (n.  glossopharyngeus)  and 
partly  on  the   sympathetic.     The   secretion   may  be   excited  by 


170  PHYSIOLOGICAL  CHEMISTRY. 

mental  emotions  and  by  irritation  of  the  glandular  nerves,  either  di- 
rectly (in  animals)  or  reflexly,  by  mechanical  or  chemical  irritation 
of  the  mucous  membrane  of  the  mouth.  Among  the  chemical  irri- 
tants the  acids  take  first  place,  while  alkalies  and  pungent  substances 
have  little  action.  Sweet-tasting  bodies,  such  as  honey,  are  said  to 
have  no  effect.  Mastication  has  great  influence  in  the  secretion  of 
parotid  saliva,  which  is  especially  marked  in  certain  herbivora. 

Human  parotid  saliva  may  be  collected  by  the  introduction  of  a 
canula  into  the  parotid  duct.  This  saliva  is  thin,  less  alkaline  than 
the  submaxillary  saliva  (the  first  drops  are  sometimes  neutral  or 
acid),  without  special  odor  or  taste.  It  contains  a  little  albumin 
but  no  mucin,  which  is  to  be  expected  from  the  construction  of  the 
gland.  It  also  contains  a  diastatic  enzyme,  which,  however,  is  ab- 
sent in  many  animals.  The  quantity  of  solids  varies  between  5  and 
16  p.  m.  The  specific  gravity  is  1.003-1.012.  Potassium  sulpho- 
cyanide  seems  to  be  present,  though  it  is  not  a  constant  constituent," 
KiJLZ  found  1.46^  oxygen,  3.2^  nitrogen,  and  in  all  66.7^  carbon 
dioxide  in  human  parotid  saliva.  The  quantity  of  closely-com- 
bined carbon  dioxide  was  62^. 

The  mixed  buccal  saliva  in  man  is  a  colorless,  faintly  opales- 
cent, slightly  ropy,  easily  frothing  liquid  without  special  odor  or 
taste.  It  is  made  turbid  by  epithelium  cells,  mucous  and  salivary 
corpuscles,  and  often  by  food  residues.  Like  the  submaxillary 
and  parotid  saliva,  on  exposure  to  the  air  it  becomes  covered 
with  an  incrustation  consisting  of  calcium  carbonate  and  a  small 
quantity  of  an  organic  substance,  or  it  gradually  becomes  cloudy. 
Its  reaction  is  alkaline,  but  occasionally  also  acid.  According 
to  Sticker,  fresh  saliva  may  be  acid  a  few  hours  after  a  meal. 
Two  or  three  hours  after  breakfast  and  four  to  five  hours  after 
dinner  the  maximum  of  acidity  occurs,  and  it  may  also  be  faintly 
acid  from  midnight  to  morning.  The  specific  gravity  varies  between 
1.002  and  1.009,  and  the  quantity  of  solids  between  5  and  10  p.m.  The 
solids,  irrespective  of  the  form-constituents  mentioned,  consist  of 
alhumiii,  mucin,  ptyalin,  and  mineral  bodies.  It  is  also  claimed 
that  urea  is  a  normal  constituent  of  the  saliva.  The  mineral  bodies 
are  alkali  chlorides,  bicarbonates  of  the  alkalies  and  calcium,  phos- 
phates, and  traces  of  sulphates  and  sulphocyanides. 


DIGESTION.  171 

Sulphocyanides,  which,  although  not  constant,  occur  in  the 
saliva  of  man  and  certain  animals,  may  be  easily  detected  by  first 
acidifying  the  saliva  with  hydrochloric  acid  and  treating  with  a  very 
dilute  solution  of  ferric  chloride.  To  make  the  test  more  conclusive 
it  is  best,  as  control,  to  take  an  equal  quantity  of  acidified  water 
and  then  add  ferric  chloride.  Another,  simpler  method,  proposed 
by  GscHEiDLEN",  consists  in  putting  in  a  drop  or  two  of  the  saliva 
on  filter-paper  which  has  previously  been  dipped  in  an  amber- 
colored  solution  of  ferric  chloride  containing  hydrochloric  acid,  and 
then  dried.  Each  drop  of  saliva  containing  sulphocyanide  will 
give  a  reddish  spot.  If  the  quantity  of  sulphocyanide  is  so  small 
that  it  cannot  be  detected  directly,  concentrate  the  saliva  after  the 
addition  of  a  little  alkali,  acidify  strongly  with  hydrochloric  acid, 
and  shake  repeatedly  with  ether,  evaporating  the  latter  after  the 
addition  of  water  containing  alkali  over  a  gentle  heat;  then  test  the 
remaining  liquid. 

Ptyalin,  or  salivary  diastase,  is  the  amylolytic  ferment  of  the 
saliva.  This  ferment  is  found  in  human  saliva,  but  not  in  that  of 
animals.  It  occurs  not  only  in  adults,  but  also  in  new-born 
infants.  Zweifel  claims  that  the  ptyalin  in  new-born  infants 
occurs  only  in  the  parotid  gland,  but  not  in  the  submaxillary.  In 
the  latter  it  appears  only  two  months  after  birth. 

Ptyalin  has  not  been  isolated  in  a  pure  form  up  to  the  present 
time.  It  was  obtained  purest  by  precipitation  with  calcium  phos- 
phate (Cohnheim).  For  the  study  or  the  demonstration  of  the 
action  of  ptyalin  we  may  use  a  watery  or  glycerin  extract  of  the 
salivary  glands,  or,  more  simply,  the  saliva  itself. 

Ptyalin,  like  other  enzymes,  is  characterized  by  its  action.  This 
consists  in  converting  starch  into  dextrin  and  sugar.  According  to 
the  common  acceptation,  soluble  starch  is  first  formed  by  this  action 
■  and  then  erythro-dextrin,  which  is  further  changed  so  that  we 
obtain  at  the  end  achroo-dextrin  and  maltose  with  a  small  admix- 
ture of  glucose.  Like  starch,  glycogen  is  also  split  by  ptyalin  into 
dextrin  and  sugar  (apparently  maltose)  upon  the  addition  of  water. 
Ptyalin  is  not  identical  with  malt  diastase;  while  the  first  acts  with 
greatest  energy  at  about  +  40°  C,  diastase  acts  best  at  -|-  50°  to 
55°  C.  (Chittenden"  and  Martin). 

Ptyalin  acts  in  faintly  alkaline,  in  neutral,  and  in  extremely  weak 
acid  solutions.  It  seems  to  act  most  energetically  in  neutral  or,  in 
a  few  cases,  in  very  faint  acid  reaction  (Chittenden  and  Schmidt). 


172  PHT810L0QIGAL  CHEMI8TBT. 

The  amount  of  action  in  the  latter  case  is  dependent  upon  several 
circumstances,  such  as  the  degree  of  dilution  and  the  presence  of 
proteids  or  peptone  (Chittenden).  Of  the  greatest  physiological 
importance,  however,  is  the  fact  that  even  very  small  quantities  of 
free  acids — not  only  a  degree  of  acidity  of  about  1  p.  m.  HCl, 
which  often  occurs  in  the  gastric  juice,  hut  even  a  smaller  quantity 
of  hydrochloric  acid  (organic  acids  are  less  active) — at  once  pre- 
vents the  action  of  the  ptyalin  and  destroys  the  enzyme.  It  is  also 
of  interest  that  boiled  stai-ch  (starch-paste)  is  more  quickly  con- 
verted into  sugar  than  unboiled.  The  time  required  to  change 
unboiled  starch  varies  with  the  kind. 

The  i-apidity  with  which  ptyalin  acts  increases,  at  least 
under  conditions  otherwise  favorable,  with  the  amount  of  enzyme 
and  a  temperature  a  little  above  -|-  40°  C.  Foreign  substances  such  as 
metallic  salts,  have  a  different  effect.  Certain  salts  even  in  small 
quantities  completely  arrest  the  action ;  for  example,  HgClg  accom- 
plishes this  result  by  the  presence  of  only  0.05  p.  m.  Other  salts, 
such  as  magnesium  sulphate,  in  small  quantities  (0.25  p.  m.)  acceler- 
ate, and  in  larger  quantities  (5  p.  m.)  check  the  action.  The  accu- 
mulation of  the  products  of  the  amylolytic  decomposition  also  checks 
the  action  of  the  saliva. 

To  show  the  action  of  saliva  or  ptyalin  on  starch  the  three 
ordinary  tests  for  glucose  may  be  used,  namely,  Moore^s  or 
Trommer's  test  or  the  Bismuth  test  (see  Chap.  XIV).  It  is  also 
necessary,  as  a  control,  to  first  test  the  starch-paste  and  the  saliva 
for  the  presence  of  glucose. 

The  quantitative  composition  of  the  mixed  saliva  must  vary  con- 
siderably, not  only  because  of  individual  differences,  but  also  because 
under  varying  conditions  there  may  be  an  unequal  division  of  the 
secretion  from  the  different  glands.  Analyses  of  the  composition 
of  human  saliva  are  given  in  the  table  on  the  opposite  page.  The 
figures  are  parts  per  1000. 

The  quantity  of  saliva  secreted  during  24  hours  cannot  be  exact- 
ly determined,  but  has  been  calculated  by  Bidder  and  Schmidt 
to  be  1500  grms.  The  most  abundant  secretion  occurs  during 
meal-times.  According  to  the  calculations  and  determinations  of 
Tuczek  in  man,  1  grm.  of  gland  should  yield  13  grms.  seci-etion 
in  the   course   of  one  hour   during  mastication.      These   figures 


DIGESTION. 


173 


Water • 

Solids • . 

Mucus  and  epithelium 

Soluble  organic  substances 
(Ptyalin  of  early  investigators) 

Sulphocyanides 

Salts  


992.9 

7.1 


1.4 

3.8 


1.9 


995.10 
4.84 


1.62 
1.34 

0.06 


1.82 


994.1 
5.9 


2.13 
1.42 

0.10 


2.19 


H  =  a 

Q    C   S 


)88.3 
11.7 


994.7 
5.3 


3.27 


1.03 


3.5-8.4 
in 

filtered 
saliva 


0.064 

to 
0.09 


s  pa 


994  2 

5.8 


2.2 
1.4 


0.04 


2.2 


Hammerbacher  found  in  1000  parts  of  the  ash  from  human  saliva 
(potash  457.2,  soda  95.9,  iron  oxide  50.11,  magnesia  1.55,  sulphuric  anhydride 
SOa)  63.8,  phosphoric  anhydride  (P2O5)  188.48,  and  chlorine  183.52. 

correspond  fairly  well  with  those  representing  the  average  secre- 
tion from  1  grm.  of  gland  in  animals,  namely,  14.2  grms.  in  the 
horse  and  8  grms.  in  oxen.  The  quantity  of  secretion  per  hour 
may  be  8  to  14  times  greater  than  the  entire  mass  of  glands,  and 
there  is  probably  no  gland  in  the  entire  body,  as  far  as  we  know  at 
present — the  kidneys  not  excepted — whose  ability  of  secretion  under 
physiological  conditions  equals  that  of  the  salivary  glands.  A  re- 
markably abundant  secretion  of  saliva  is  induced  by  pilocarpin, 
while  atropin,  on  the  contrary,  prevents  it. 

Though  an  abundant  secretion  of  saliva  is  produced,  as  a  rule, 
by  an  increased  supply  of  blood,  still  it  is  not  a  simple  filtration 
process,  as  seen  from  the  following  circumstances.  The  secretion- 
pressure  is  greater  than  the  blood-pressure  in  the  carotid,  and  in 
poisoning  by  atropin,  which  paralyzes  the  secretory  nerves,  an  in- 
creased supply  of  blood  is  produced  by  irritation  of  the  chorda,  but 
no  secretion  (Heidenhain).  The  salivary  glands  have  moreover 
a  specific  property  of  eliminating  certain  substances,  such  as  potas- 
sium salts  (Salkowski),  iodine  and  bromine  combinations,  but  not 
others,  such  as  iron  combinations.  It  is  also  noticeable  that  the 
saliva  is  richer  in  solids  when  it  is  eliminated  quickly  by  gradually- 
increased  irritation,  and  in  larger  quantities  than  when  the  secre 


174  PHYSIOLOGICAL   CHEMI8TRT. 

tion  is  slower  and  less  abundant  (Heidenhain").  The  amount  of 
salts  increases  also  to  a  certain  degree  by  an  increasing  rapidity  of 
elimination  (Heidekhain,  Werthee,  Langley  and  Fletcher, 
Novy). 

The  chemical  changes  taking  place  during  secretion  are  un- 
known, but  it  is  probable  that,  like  the  secretion  processes  in  gen- 
eral, the  secretion  of  saliva  is  closely  connected  with  the  processes 
in  the  cells,  HEiDE]srHAi]sr  claims  that  the  mucin-cells  of  the  sub- 
maxillary gland  are  destroyed  (while  Ewald  and  Stohr  claim  that 
they  only  lose  mucin),  and  in  the  period  of  rest  the  mucin  reap- 
pears in  these  cells.  These  observations  still  do  not  throw  any  light 
upon  the  chemical  processes  going  on. 

The  Physiological  Importance  of  the  Saliva.  The  quantity  of 
water  in  the  saliva  renders  possible  the  effects  of  certain  bodies  on 
the  organs  of  taste,  and  it  also  serves  as  a  solvent  for  a  part  of  the 
nutritive  substances.  The  importance  of  the  saliva  in  mastication 
is  especially  marked  in  herbivora,  and  there  is  no  question  of  its 
importance  in  facilitating  the  act  of  swallowing.  The  power  of 
converting  starch  into  sugar  does  not  belong  to  the  saliva  of  all 
animals,  and  even  when  it  possesses  this  property  the  intensity 
varies  in  different  animals.  In  man,  whose  saliva  forms  sugar  ra- 
pidly, a  formation  of  sugar  from  (boiled)  starch  undoubtedly  takes 
place  in  the  mouth,  but  how  far  this  action  goes  on  after  the  morsel 
has  entered  the  stomach  depends  upon  the  rapidity  with  which  the 
acid  gastric  juice  mixes  with  the  swallowed  food,  and  also  upon  the 
relative  amounts  of  the  gastric  juice  and  food  in  the  stomach.  The 
large  quantity  of  water  which  is  swallowed  with  the  saliva  must 
be  absorbed  and  pass  into  the  blood,  and  it  must  go  through  an 
intermediate  circulation  in  the  organism.  Thus  the  organism  pos- 
sesses in  the  saliva  an  active  medium  by  which  a  constant  stream, 
conveying  the  dissolved  and  finely-divided  bodies,  passes  into  the 
blood  from  the  intestinal  canal  during  digestion. 

Salivari  Calculi.  The  so-called  tartar  is  yellow,  gray,  yellowish  gray, 
brown  or  black,  and  has  a  stratified  structure.  It  may  contain  more  than  200 
p.  m.  organic  substances,  which  consist  of  mucin,  epithelium,  and  lepto- 
THKix.  The  chief  part  of  the  inorganic  constituents  consists  of  calcium  car- 
bonate and  phosphate.  The  salivary  stone  may  vary  in  size  from  the  size  of 
a  small  grain  to  that  of  a  pea  or  still  larger  (a  salivary  stone  has  been  found 
weighing  18.6  grms.),  and  it  contains  a  variable  quantity  of  organic  substances, 
50-380  p.  m.,  which  remain  on  extracting  the  stone  with  hydrochloric  acid. 
The  chief  inorganic  constituent  is  calcium  phosphate. 


DIGESTION.  175 

II.  The  Glands  of  the  Mucous  Membrane  of  the  Stomach, 
and  the  Gastric  Juice. 

Since  of  old,  the  glands  of  the  mucous  coat  of  the  stomach  have 
been  divided  into  two  distinct  kinds.  The  kind  occurring  in 
the  greatest  abundance,  and  the  most  important  in  size,  especially 
in  the  fundus,  has  been  named  fundus  glands,  also  ken"net  or 
PEPTONE  glands.  The  other,  which  is  found  in  the  neigh- 
borhood of  the  pylorus,  has  received  the  name  of  pyloric  glands, 
sometimes  also,  though  incorrectly,  mucous  glaads.  The  mucous 
coating  of  the  stomach  is  covered  to  its  entire  extent  with  a  layer 
of  cylindrical  epithelium,  which  is  considered  as  consisting  exclu- 
sively of  follicles,  small  cup-shaped  cavities  which  by  a  mucus-like 
metamorphosis  produce  the  protoplasm. 

The  fundus  glands  contain  two  kinds  of  cells:  adelomoe- 
PHic  or  principal  cells,  and  delomorphic  or  parietal  cells,  the 
latter  formerly  called  rennet  or  pepsin  cells.  Both  kinds 
consist  of  protoplasm  rich  in  proteids;  but  their  relationship 
to  coloring  matters  seems  to  show  that  the  two  albuminous  bodies 
are  not  identical.  The  nucleus  must  consist  chiefly  of  nuclein. 
Besides  the  above-mentioned  constituents  the  fundus  glands  con- 
tain as  more  specific  constituents  two  zymogens,  which  are  the 
mother-substances  of  the  pepsin  and  the  rennet,  besides  a  small 
quantity  of  fat  and  cholesterin. 

The  pyloric  glands  contain  cells  which  are  generally  considered 
as  related  to  the  above-mentioned  chief  cells  of  the  fundus  glands. 
As  these  glands  were  formerly  thought  to  contain  a  larger  quantity 
of  mucin,  they  were  also  called  mucous  glands.  According  to 
Heidenhain,  independent  of  the  cylindrical  epithelium  of  the 
excretory  passages,  they  take  no  part  worthy  of  mention  in  the 
formation  of  mucus,  which,  according  to  his  views,  is  effected  by 
the  epithelium  covering  the  mucous  membrane.  The  pyloric 
glands  also  seem  to  contain  the  zymogens  referred  to  above.  Alkali 
chlorides,  alkali  phosphates,  and  calcium  phosphates  are  found  in 
the  mucous  coating  of  the  stomach. 

The  Gastric  Juice.  The  experiments  of  Helm  and  Beaumont 
on  persons  with  gastric  fistula  led  to  the  suggestion  that  gastric 
fistulas  be  made  on  animals,  and  this  operation  was  first  performed 


176  PHYSIOLOGICAL  CHEMISTRY. 

by  Bassow  in  1842  on  a  dog.  Vekkeuil  performed  the  same  on  a 
man  in  1877  with  successful  results.  These  fistulas  in  animals 
afford  an  excellent  means  of  studying  the  secretion  of  gastric 
juice  and  also  the  stomachic  digestion. 

In  a  fasting  condition  the  mucous  coat  is  often  nearly  dry; 
sometimes,  especially  on  certain  herbivora,  it  is  covered  with  a  layer 
of  viscid  so-called  mucus.  If  food  is  introduced  into  the  stomach, 
or  if  the  mucous  membrane  is  irritated  in  some  way,  then  a  secre- 
tion of  a  thin,  acid  fluid,  the  real  gastric  juice,  takes  place.  The 
secretion  may  be  produced  by  mechanical  or  thermal  irritation  (in- 
troduction of  cold  water  or  pieces  of  ice  into  the  stomach),  or  by 
chemical  irritants.  Among  the  latter,  alcohol  and  ether  when  in 
too  great  concentration  do  not  produce  a  physiological  secretion, 
but  a  transudation  of  a  neutral  or  faintly  alkaline  fluid  con- 
taining albumin  (Cl.  Bert^ard).  To  this  class  of  irritants 
belong  carbon  dioxide  and  hydrochloric  acid;  the  last  especially 
increases  the  secretion  of  pepsin  (Jaworsky),  spices,  meat 
extracts,  neutral  salts,  such  as  NaCl  (which  acts  like  alcohol  in 
too  great  concentration),  and  alkali  carbonates.  The  alkali 
carbonates  are  supposed  by  certain  investigators  to  first  neutralize, 
and  then  produce  a  continuous  secretion  of,  acid  gastric  juice. 
The  statements  in  regard  to  the  action  of  different  bodies 
in  the  secretion  of  gastric  juice  are  still  rather  uncertain  and 
often  contradictory. 

Several  investigators  state  that  the  secretion  of  gastric  juice 
may  be  stimulated  by  reflex  means.  After  the  introduction  of 
water  into  the  stomach  a  proportionally  poor  and  scanty  secretion 
takes  place,  while  on  the  contrary  the  introduction  of  digestible 
foods  causes  a  more  abundant  and  continuous  secretion  (Schiff, 
Heidenhain).  But  in  these  cases  the  secretion  does  not  take 
place  immediately,  but  only  after  the  absorption  of  the  soluble 
bodies  has  commenced.  This  fact  justifies  the  usual  custom  of 
commencing  a  meal  with  fluid  nutritives  such,  as  soup. 

The  Qualitative  and  Quantitative  Composition  of  the  Gastric 
Juice.  The  gastric  juice,  which  can  hardly  be  obtained  pure  and 
free  from  residues  of  the  food  or  from  mucus  and  saliva,  is  a  clear, 
or  only  very  faintly  cloudy,  and  in  man  nearly  colorless  fluid  of  an 
insipid,  acid  taste  and  strong  acid  reaction.     It  contains,  as  form- 


DIGESTION. 


177 


elements,  glandular  cells  or  their  nuclei,  mucus-corpuscles ,  and 
more  or  less  changed  cylindrical  ejnthelium. 

The  acid  reaction  of  the  gastric  juice  depends  on  the  presence 
of  free  acid,  which,  as  we  have  learned  from  the  investigations  of 
C.  Schmidt,  Richet,  and  others,  seems,  under  physiological  con- 
ditions, to  consist  only  of  hydrochloric  acid.  Under  special  con- 
ditions, as  after  a  meal  rich  in  carbohydrates,  lactic  acid  occurs  in 
the  contents  of  the  stomach,  and  even  acetic  and  butyric  acid. 
The  quantity  of  free  hydrochloric  acid  in  the  gastric  juice  of  sheep 
is  about  1,2  p.  m.,  and  in  dogs  3  p.  m.  Eichet  found  as  average 
for  80  determinations  of  human  gastric  juice  1.7  p.  m.  free 
liydrocliloric  acid,  with  a  variation  between  0.5  and  3  p.  m. 
According  to  Szabo  and  Ewald  and  Boas,  the  human  gastric 
juice  contains  usually  about  2-3  p.  m.  HCl. 

The  gastric  juice  seems  to  contain  no  coagulable  albumin,  but 
contains  traces  of  peptone  or  albumose  (?).  Among  the  organic 
bodies  a  little  mucin  is  found,  and  besides,  especially  in  man,  two 
enzymes,  pepsin  and  rennet. 

The  specific  gravity  of  gastric  juice  is  low,  1.001-1.010.  It  is 
therefore  correspondingly  poor  in  solids.  As  examples  of  the 
composition  of  different  kinds  of  gastric  juice  the  analyses  of 
C.  Schmidt  are  here  given.  It  must  be  remarked  that  the  human 
gastric  juice  analyzed  was  diluted  by  saliva  and  water  and  should 
therefore  not  be  considered  as  normal.  The  figures  are  parts  per 
1000. 


Water 

Solids 

Organic  substance 

NaCl 

CaCl!, 

KCl 

NH4CI 

Free  hydrochloric  acid  (HCl) 

Ca3(P04)2 

Mg<,(P04), 

FePO^ 


Human  Gas- 

Gastric 

Gastric 

tric  Juice 

Juice  from 

Juice  from 

mixed  with 

Dog  free 

Dog  contain- 

Saliva. 

from  Saliva. 

ing  Saliva. 

994.40 

973.0 

971.2 

5.60 

27.0 

28.8 

3.19 

17.1 

17.3 

1.46 

2.5 

3.1 

0.06 

0.6 

1.7 

0.55 

1.1 

1.1 

0.5 

0.5 

0.20 

3.1 

2.3 

) 

1.7 

2.3 

I     0.12 

0.2 

0.3 

) 

0.1 

0.1 

Gastric 
Juice  of 
Sheep. 


986.15 
13.85 
4.05 
4.36 
0.11 
1.52 
0.47 
1.23 
1.18 
0.57 
0.33 


178  PHYSIOLOGICAL   CHEMISTRY. 

The  physiologically  important  constituents,  besides  free  nyaro- 
chlorlc  acid,  sire  pepsin  and  I'ennet. 

Pepsin.  This  enzyme  is  found,  with  the  exception  of  certain 
fishes,  in  all  vertebrata  thus  far  investigated. 

Pepsin  occurs  in  adults  and  in  new-born  infants.  This  condi- 
tion is  different  in  new-born  animals.  While  in  a  few  herbivora, 
such  as  the  rabbit,  pepsin  occurs  in  the  mucous  coat  before  birth, 
this  enzyme  is  entirely  absent  at  the  birth  of  those  carnivora  which 
have  thus  far  been  examined,  such  as  the  dog  and  cat. 

In  various  invertebrates  a  fermeut  has  also  been  found  whicli  has  a  prote- 
olytic action  in  acid  solutions.  Krukenberg  has  shown  that  this  enzyme, 
nevertheless  is  not  in  all  animals,  identical  with  ordinary  pepsin.  Darwin  has 
further  found  that  certain  plants  which  feed  upon  insects  secrete  an  acid 
juice  which  dissolves  albumin,  but  it  is  still  doubtful  whether  these  plants 
contain  any  pepsin,  v.  Goritp  Besanez  has  isolated  from  vetch-seed  an 
enzyme  which  acts  like  pepsin,  but  whose  identity  with  pepsin  is  doubtful. 

Pepsin  is  as  difficult  to  isolate  in  a  pure  condition  as  other 
enzymes.  The  purest  pepsin  was  that  prepared  by  Brucke  and 
SuNDBERG  ;  this  gave  negative  results  with  most  reagents  for 
albumin.  Pepsin,  therefore,  does  not  seem  to  be  a  true  albuminous 
substance.  It  is,  at  least  in  the  impure  condition,  soluble  in  water 
and  glycerin.  It  is  precipitated  by  alcohol,  but  only  slowly  de- 
stroyed. It  is  quickly  destroyed  by  heating  its  watery  solution  to 
boiling ;  in  the  dry  state  it  can,  on  the  contrary,  be  heated  to  over 
100°  0.  without  losing  its  physiological  action.  The  only  property 
which  is  characteristic  of  pepsin  is  that  it  dissolves  albuminous 
bodies  in  acid,  but  not  in  neutral  or  alkaline,  solutions  with  the 
formation  of  albumoses  and  peptones. 

The  methods  for  the  preparation  of  relatively  pure  pepsin  de- 
pend, as  a  rule,  upon  its  property  of  being  thrown  down  with 
finely-divided  precipitates  of  other  bodies,  such  as  calcium  phos- 
phate or  cholesterin.  The  rather  complicated  method  of  Britcke 
and  SuNDBERG  is  based  upon  this  property.  A  relatively  pure 
pepsin  solution  intended  for  digestion  tests  and  of  effective  action 
may  be  prepared  by  the  following  method  as  suggested  by  Maly. 
The  mucous  membrane  (of  the  pig's  stomach)  is  treated  with  water 
containing  phosphoric  acid,  and  the  filtrate  precipitated  by  lime- 
water;  the  precipitate,  which  contains  the  pepsin,  is  then  dissolved 
in  water  by  the  addition  of  hydrochloric  acid,  and  the  salts  removed 
by  dialysis,  by  which  means  the  pepsin  which  does  not  diffuse  re- 
mains in  the  dialyzer.      A  pepsin  solution  somewhat  impure  but 


DIGESTION.  179 

active  and  not  liable  to  spoil  may  be  obtained  if,  as  suggested  by 
V.  WiTTiCHS,  we  extract  the  finely-divided  mucous  membrane  with 
glycerin,  or  better  with  glycerin  which  contains  1  p.  m.  HCl.  To 
each  part  by  weight  of  the  mucous  coat  add  10-30  parts  glycerin. 
This  is  filtered  after  8-14  days.  The  pepsin  (together  with  much 
albumin)  may  be  precipitated  by  alcohol  from  this  extract.  If  this 
■extract  is  to  be  used  directly  for  digestion  tests,  then  to  100  c.  c.  of 
water  which  has  been  acidified  with  1-4  p.  m.  HOI  add  2-3  c.  c.  of 
the  extract. 

For  digestion  tests  an  infusion  of  the  mucous  membrane  of  the 
stomach  may  be  used  directly  in  many  cases.  The  mucous  coat  is 
carefully  washed  with  water  (if  a  pig's  stomach  is  used)  and  finely 
<}ut;  if  a  calf's  stomach  is  employed,  only  tlie  upper  layer  of  the 
mucous  coat  is  scraped  off  with  a  watch-glass  or  the  back  of  a  knife. 
The  pieces  of  mucous  membrane  or  the  slimy  masses  obtained  by 
scraping  are  rubbed  with  pure  quartz-sand,  treated  with  acidified 
water,  and  allowed  to  stand  for  24  hours  in  a  cool  place  and  then 
filtered. 

In  the  preparation  of  artificial  gastric  juice  that  part  only  of  the 
mucous  coat  richest  in  pepsin  is  used,  the  pyloric  is  of  little  value. 
A  strong,  impure  infusion  may  generally  be  obtained  from  the 
pig's  stomach,  while  a  relatively  pure  and  powerful  infusion  is  ob- 
tained from  the  stomach  of  birds  (hens).  The  stomachs  of  fish 
(pike)  also  yield  a  tolerably  pure  and  active  infusion.  An  active 
^nd  rather  pure  artificial  gastric  juice  may  be  prepared  by  scraping 
the  inner  layers  of  a  calf's  stomach  from  which  the  pyloric  end  has 
been  removed.  For  a  medium-sized  calf's  stomach  1000  c.  c.  of 
acidified  water  must  be  used. 

The  degree  of  acidity  required  in  the  infusion  depends  upon 
the  use  to  which  the  gastric  juice  is  to  be  put.  If  it  is  to  be  em- 
ployed in  the  digestion  of  fibrin,  an  acidity  of  1  p.  m.  HCl  must 
be  selected,  while,  on  the  contrary,  if  it  is  to  be  used  for  the  diges- 
tion of  hard-boiled -egg  albumin,  an  acidity  of  2-3  p.  m.  HCl  is 
preferable.  This  last-mentioned  degree  of  acidity  is  generally  the 
better,  because  the  infusion  is  preserved  thereby,  and  at  all  events 
it  is  so  rich  in  pepsin  that  it  may  be  diluted  with  water  until  it  has 
an  acidity  of  1  p.  m.  HCl  without  losing  any  of  its  solvent  action 
on  unboiled  fibrin. 

The  Action  of  Pepsin  on  Proteids.  Pepsin  is  inactive  in  neutral 
or  alkaline  reactions,  but  in  acid  liquids  it  dissolves  coagulated 
albuminous  bodies.  The  proteid  always  swells  and  becomes  trans- 
parent before  it  dissolves.  Unboiled  fibrin  swells  up  in  a  solution 
containing  1  p.  m.  HCl,  forming  a  gelatinous  mass,  and  does  not 
■dissolve  at  ordinary  temperature  within  a  couple  of  days.     "Upon 


180  PHYSIOLOGICAL   CHEMISTBT. 

the  addition  of  a  little  pepsin,  however,  this  swollen  mass  dissolves 
quickly  at  an  ordinary  temperature.  Hard-boiled-egg  albumin,  cut 
in  thin  pieces  with  sharp  edges,  is  not  perceptibly  changed  by  dilute 
acid  (3-4  p.  m.  HCl)  at  the  temperature  of  the  body  in  the  course 
of  several  hours.  But  the  simultaneous  presence  of  pepsin  causes 
the  edges  to  become  clear  and  transparent,  blunt  and  swollen,  and 
the  albumin  gradually  dissolves. 

Erom  what  has  been  said  above  in  regard  to  pepsin,  it  follows 
that  albumin  may  be  employed  as  a  means  of  detecting  pepsin  in 
liquids.  Fibrin  may  be  employed  as  well  as  hard-boiled-egg  albu- 
min, which  latter  is  used  in  the  form  of  slices  with  sharp  edges. 
As  the  fibrin  is  easily  digested  at  the  normal  temperature,  while 
the  pepsin  test  with  egg-albumin  requires  the  temperature  of  the 
body,  and  as  the  test  with  fibrin  is  somewhat  more  delicate,  it  is 
often  preferred  to  that  with  egg-albumin.  When  we  speak  of  the 
^'pepsin  test"  without  further  explanation,  we  ordinarily  under- 
stand it  as  the  test  with  fibrin. 

This  test  nevertheless  requires  care.  The  unboiled  fibrin  may 
be  dissolved  by  acid  alone  without  pepsin,  but  this  generally 
requires  more  time.  In  testing  with  unboiled  fibrin  at  normal 
temperature,  it  is  advisable  to  make  a  control  test  with  another 
portion  of  the  same  fibrin  with  acid  alone.  Since  at  the  tempera- 
ture of  the  body  unboiled  fibrin  is  easier  dissolved  by  acid  alone,  it 
is  best  always  to  work  with  boiled  fibrin. 

As  pepsin  has  not,  thus  far,  been  prepared  in  a  positively  pure 
condition,  it  is  impossible  to  determine  the  absolute  quantity  of 
pepsin  in  a  liquid.  It  is  only  possible  to  compare  the  relative 
amounts  of  pepsin  in  two  or  more  liquids,  which  may  be  done  in 
several  ways.  As  the  best  of  these  we  give  the  following  method 
as  suggested  by  Brucke. 

If  two  pepsin  solutions  A  and  B  are  to  be  compared  with  each  other 
relatively  to  the  amounts  of  pepsin  they  contain,  they  must  first  be  brought 
to  the  proper  degree  of  acidity,  about  1  p.  m.  HCl,  care  being  taken  that  one  is 
not  more  diluted  than  the  other.  Then  prepare  a  large  number  of  specimens 
of  each  solution  by  diluting  with  hydrochloric  acid  of  1  p.  m.  HCl,  so  that  they 
contain  respectively  |,  |,  |,  yV'  A'  ^^^  ^o  on,  the  amount  of  pepsin  in  the 
original  liquid  being  1.  If  the  original  quantity  of  pepsin  in  the  two  liquids 
is  designated  by  p  and  p',  we  then  have  the  two  series  of  liquids  : 

A  B 

Ip  Ip' 

kp  W 

\P  iP 

h>  Ip 

T^P  t\P' 

■hP  -hP 


DIGESTION.  181 

Then  a  small  piece  of  boiled-egg  albumin,  obtained  by  cutting  thin  slices 
■with  a  cork-cutter,  is  placed  in  each  test,  or  a  small  flake  of  fibrin  is  added. 
Of  course  care  must  be  taken  to  add  the  same-sized  slice  of  egg-albumin  or 
flake  of  fibrin.  Now  observe  and  note  exactly  the  time  when  each  test  of  the  two 
series  begins  to  digest  and  when  it  ends,  and  it  will  be  found  that  certain  tests 
of  one  series  make  about  the  same  progress  as  certain  tests  of  the  other  series. 
It  may  be  inferred  from  this  that  they  contain  about  the  same  quantity  of 
pepsin.  As  example,  it  is  found  in  one  series  of  tests  that  the  digestive 
rapidity  of  the  tests  p  l,p^^,  p  ^V  is  about  the  same  as  the  tests  p'  |,  p'  I,  p'  i; 
therefore  we  conclude  that  the  liquid  A  is  about  four  times  as  rich  in  pepsin  as 
the  liquid  B. 

The  rapidity  of  the  pepsin  digestion  depends  on  several  circum- 
stances. Thus  different  acids  are  unequal  in  their  action;  hydro- 
chloric acid  shows  a  more  powerful  action  than  any  other,  whether 
an  organic  or  an  inorganic  acid.  The  degree  of  acidity  is  also  of 
the  greatest  importance.  The  most  effective  degree  of  acidity  is 
not  the  same  with  hydrochloric  acid  for  different  albuminous 
bodies.  For  fibrin  it  is  0.8-1  p.  m.,  for  myosin,  casein,  and  vege- 
table albumin  about  1  p.  m.,  for  hard-boiled-egg  albumin,  on  the 
contrary,  about  2.5  p.  m.  The  rapidity  of  the  digestion  increases, 
at  least  to  a  certain  point,  with  the  quantity  of  pepsin  present,  un- 
less the  pepsin  added  is  contaminated  by  a  large  quantity  of  pro- 
ducts of  digestion,  which  may  prevent  its  action.  The  accumulation 
of  products  of  digestion  disturb  the  digestion.  At  low  temperatures 
the  pepsin  acts  slowly  in  warm-blooded  animals,  and  it  is  nearly 
without  action  at  a  temperature  below  +  3°  0.  With  increasing 
temperature  the  rapidity  of  digestion  increases,  and  at  about  40°  C. 
it  is  greatest.  The  pepsin  of  cold-blooded  animals  also  acts  in  the 
neighborhood  of  0°  C.  If  the  swelling  up  of  the  proteid  is  pre- 
vented, as  by  the  addition  of  neutral  salts,  such  as  NaCl  in  sufficient 
amounts,  or  by  the  addition  of  bile  to  the  acid  liquid,  the  digestion 
can  be  prevented.  Foreign  bodies  of  different  kinds  can  produce 
different  actions,  in  which  naturally  the  variable  quantities  in  which 
they  are  added  are  of  the  greatest  importance.  Salicylic  acid  and 
carbolic  acid  hinder  the  digestion,  while  arseuious  acid  promotes  it 
(Chitten'DEn),  and  hydrocyanic  acid  is  relatively  indifferent. 
Alcohol  in  large  quantities  (10^  and  above)  disturbs  the  digestion, 
while  small  quantities  act  indifferently.  Metallic  salts  in  very  small 
quantities  may  indeed  sometimes  accelerate  digestion,  but  otherwise 
they  tend  to  retard  it.  The  action  of  metallic  salts  in  different  cases 
can  be  explained  in  different  ways,  but  they  often  seem  to  form 


182  PHYSIOLOGICAL   CHEMISTRY. 

with  proteids  insoluble  or  difficultly-soluble  combinations.  The 
alkaloid  compounds  may  also  decrease  the  pepsin  digestion  (Chit- 
tenden and  Allen).  A  very  large  number  of  observations  have 
been  made  in  regard  to  the  action  of  foreign  substances  on  artificial 
pepsin  digestion,  but  as  these  observations  have  not  given  any 
direct  result  in  regard  to  the  action  of  these  same  substances  on 
natural  digestion,  we  will  not  here  further  discuss  them. 

Tlie  Products  of  the  Digestion  of  Proteids  by  Means  of  Pepsin 
and  Acid.  In  the  digestion  of  nucleo-albumin  an  insoluble  residue 
of  nuclein  always  remains.  JFibrin  also  yields  an  insoluble  residue, 
which  consists,  at  least  in  great  part,  of  nuclein,  derived  from  the 
form-elements  enclosed  in  the  blood-clot.  This  residue  which 
remains  in  the  digestion  of  certain  albuminous  bodies  is  called 
dyspeptone  by  Meissner.  If  the  solution  is  filtered  after  a  com- 
plete digestion  and  neutralized,  it  gives  in  different  cases  a  more 
or  less  abundant  precipitate  of  acid  albuminate,  or  a  mixture  of 
albuminates  called  parapeptone  by  Meissner.  After  filtering  this 
precipitate  and  concentrating  the  filtrate  again,  some  proteid  often 
separates.  If  this  precipitate  be  filtered,  the  filtrate  will  now  con- 
tain alhumoses  and  peptones  in  the  ordinary  sense,  while  the  so- 
called  true  peptone  of  Kuhne  may  sometimes  be  entirely  absent, 
and  in  general  is  obtained  in  quantity  worth  mentioning  only 
after  a  more  continuous  and  intensive  digestion.  The  relationship 
between  the  albumoses  and  peptones  in  the  ordinary  sense  changes 
very  much  in  different  cases  and  in  the  digestion  of  various 
albuminous  bodies.  For  instance,  a  larger  quantity  of  primary 
albumoses  is  obtained  from  fibrin  than  from  hard-boiled-egg  albu- 
min or  from  the  proteids  of  meat.  In  the  digestion  of  unboiled 
fibrin  an  intermediate  product  may  be  obtained  in  the  earlier  stages 
of  the  digestion — a  globulin  which  coagulates  at  -f-  55°  0.  (Hasb- 
broek).  For  information  in  regard  to  the  different  albumoses  and 
peptones  which  are  formed  in  pepsin  digestion,  the  reader  is 
referred  to  previous  pages  (25-28.). 

KiJHNE  claims  that  the  albumoses  and  peptones  are  the  final 
products  in  the  pepsin  digestion.  Hoppe-Seyler  claims,  on  the 
contrary,  that  amido-acids,  leucin  and  tyrosin,  are  also  found. 
Hirschler  has  tried  to  confirm  this  view  by  his  investigations. 
The  methods  used  by  him  do  not  seem  to  be   quite  trustworthy 


DIGESTION.  183 

(Neumeistek),  and  according  to  Kuhne  and  Neumeister  the 
amido-acids  found  in  the  specified  cases  as  products  of  digestion 
were  derived  from  the  contamination  of  the  gastric  juice  employed. 

Action  of  Pepsin  Hydrochloric  Acid  on  other  Bodies.  The  gela- 
tine-fonning  substance  of  the  connective  tissue,  of  the  cartilage  and 
of  the  bones,  from  which  last  the  acid  only  dissolves  the  inorganic 
substances,  is  converted  into  gelatine  by  digesting  with  gastric 
juice.  The  gelatine  is  further  changed  so  that  it  loses  its  property 
of  gelatinizing  and  is  converted  into  a  so-called  gelatine  peptone 
(see  page  38).  True  mucin  (from  the  submaxillary)  is  dissolved 
by  the  gastric  juice  and  yields  a  substance  similar  to  peptone  and  a 
reducible  substance  similar  to  that  obtained  by  boiling  with  a 
mineral  acid.  Elastin  is  dissolved  more  slowly  and  yields  the 
above-mentioned  substance  (page  36).  Keratin  and  the  epidermis 
formation  are  insoluble.  Nuclein  is  not  dissolved  and  the  cell- 
nucleus  is  therefore  insoluble  in  gastric  juice.  The  animal  cell- 
membrane  is,  as  a  rule,  more  easily  dissolved  the  nearer  it  stands  to 
elastin,  and  it  dissolves  with  greater  difficulty  the  more  closely  it  is 
related  to  keratin.  The  membrane  of  the  pla7it-cell  is  not  dissolved. 
The  oxyhmmoglobin  is  changed  into  haematin  and  acid  albuminate, 
the  latter  undergoing  further  digestion.  It  is  for  this  reason  that 
blood  is  changed  into  a  dark-brown  mass  in  the  stomach.  The 
gastric  juice  does  not  act  on  fat,  but,  on  the  contrary,  on  fatty 
tissue  in  which  it  dissolves  the  cell-membrane,  setting  the  fat  free. 
Human  gastric  juice,  according  to  Leube,  can  convert  cane-sugar 
into  grape-sugar.  Pepsin  hydrochloric  acid  does  not  seem  to  take 
any  part  in  the  decompositions  and  cleavages,  which  the  carbo- 
hydrates may  undergo  in  the  stomach. 

Pepsin  alone,  as  above  stated,  has  no  action  on  proteids,  and  an 
acid  of  the  intensity  of  the  gastric  juice  can  only  very  slowly,  if  at 
all,  dissolve  coagulated  albumin  at  the  temperature  of  the  body. 
Pepsin  and  hydrochloric  acid  together  not  only  act  more  quickly, 
but  qualitatively  they  act  otherwise  than  the  acid  alone.  If  liquid 
proteid  is  digested  with  hydrochloric  acid  of  2  p.  m.,  it  is  con- 
verted into  acid  albuminates;  but  if  the  acid  is  replaced  by  pepsin, 
the  formation  of  syntonin  takes  place  essentially  slower  under  the 
same  conditions  (Meissj^er).  From  this  it  is  inferred  that  a  part 
of  the  hydrochloric  acid  is  combined  with  the  pepsin,  and  we  have 


184  PHYSIOLOGICAL   CHEMISTRY. 

here  a  proof  of  the  existence  of  a  paired  acid,  called  by  C.  Schmidt 

pepsin  hydrochloric  acid. 

It  has  been  further  suggested  that  this  hypothetical  acid  is  possibly  decom- 
posed into  pepsin  and  a  free  acid,  which  in  statu  nascendi  dissolves  proteids 
to  a  certain  degree.  The  pepsin  set  free  reunites  with  a  new  portion  of  acid, 
forming  pepsin  hydrochloric  acid,  and  in  contact  with  proteids  is  further 
decomposed  as  above  described.  It  is  hardly  necessary  to  mention  that  this 
statement  is  only  an  unproved  hypothesis. 

Rennet  or  chtmosin  (Deschamps)  is  the  second  enzyme  of  the 
gastric  juice.  According  to  Boas,  it  is  found  in  human  gastric 
under  physiological  conditions,  but  may  be  absent  under  special 
pathological  conditions,  such  as  carcinoma,  atrophy  of  the  mucous 
membrane,  and  certain  chronic  catarrhs  (Boas,  Johnson",  Klem- 
pekee).  It  is  habitually  found  in  the  neutral,  watery  infusion  of 
the  fourth  stomach  of  the  calf  and  sheep,  especially  in  an  infusion 
of  the  fundus  part.  In  other  mammalia  and  in  birds  it  is  seldom 
found,  and  in  fishes  hardly  ever  in  the  neutral  infusion.  Instead 
of  this  rennet-forming  substance  a  rennet  zymogen,  from  which  the 
rennet  is  formed  by  the  action  of  an  acid  is  always  found. 

Eennet  is  just  as  difficult  to  prepare  in  a  pure  state  as  the  other 
enzymes.  The  purest  rennet  enzyme  thus  far  obtained  did  not  give 
the  ordinary  albumin  reactions.  On  heating  its  solutions  it  is  de- 
stroyed, and  indeed  more  easily  in  acid  than  in  neutral  solutions. 
If  an  active  and  strong  infusion  of  a  mucous  coat  in  water  contain- 
ing 3  p.  m.  HCl  is  heated  to  37-40°  C.  for  48  hours,  the  rennet  is 
destroyed,  while  the  pepsin  remains.  A  pepsin  solution  free  from 
rennet  can  be  obtained  in  this  way.  Eennet  is  characterized  by  its 
physiological  action,  which  consists  in  coagulating  milk  or  a  casein 
solution  containing  lime,  if  neutral  or  faintly  alkaline. 

Rennet  may  be  carried  down  by  other  precipitates  like  other 
enzymes,  and  thus  may  be  obtained  relatively  pure.  It  may  also  be 
obtained,  contaminated  with  a  great  deal  of  proteids,  by  extracting 
the  mucous  coat  of  the  stomach  with  glycerin. 

A  comparatively  pure  solution  of  rennet  may  be  obtained  in  the 
following  way.  An  infusion  of  the  mucous  coat  of  the  stomach  in 
hydrocholoric  acid  is  prepared  and  then  neutralized,  after  which  it 
is  repeatedly  shaken  with  new  quantities  of  magnesium  carbonate 
until  the  pepsin  is  precipitated.  The  filtrate,  which  should  act 
strongly  on  milk,  is  precipitated  by  basic  lead  acetate,  the  preci- 
pitate decomposed  with  very  dilute  sulphuric  acid,  the  acid  liquid 
filtered  and  treated  with  a  solution  of  stearin  soap.     The  rennet  is 


DIGESTION.  185 

thrown  down  by  the  fatty  acids  set  free,  and  when  these  last  are 
placed  in  water  and  removed  by  shaking  with  ether,  the  rennet  re- 
mains in  the  watery  solution. 

A  fasting  animal  cannot  secrete  a  strongly-acid  gastric  juice 
The  acid  of  the  gastric  juice  then  cannot  be  derived  from  the  foods, 
but  must  originate  in  the  mucous  coat.  As  the  pyloric  glands, 
which  contain  no  delomorphic  cells,  secrete  an  alkaline  secretion, 
while  the  fundus  glands,  in  which  such  cells  occur,  yield  an  acid 
secretion,  it  is  generally  assumed  with  Heidenhain  that  the  delo- 
morphic cells  are  of  special  importance  in  the  secretion  of  free 
hydrochloric  acid — a  statement  which  other  observations  tend  to 
confirm.  That  the  hydrochloric  acid  must  originate  from  the  chlo- 
rides of  the  blood  is  evident;  and  these  latter  must  therefore  un- 
dergo a  decomposition  with  the  setting  free  of  hydrochloric  acid. 
This  decomposition  has  been  considered  as  an  electrolysis,  but  the 
opinion  has  also  been  held  that  it  may  be  caused  by  some  organic 
acid  formed  in  the  mucous  membrane  (Brtjcke). 

Maly  has  called  attention  to  the  fact  that,  on  account  of  the 
presence  of  a  large  quantity  of  free  carbon  dioxide  in  the  blood  and 
the  avidity  of  the  same,  there  must  be  present  among  the  numerous 
combinations  of  acids  and  bases  which  exist  in  the  serum  traces  of 
free  hydrochloric  acid  in  addition  to  acid  salts.  As  these  traces  of 
hydrochloric  acid  are  separated  from  the  blood  by  means  of  rapid 
diffusion  by  the  glands,  the  action  of  the  carbon  dioxide  must  set 
free  new  traces  of  hydrochloric  acid  in  the  blood,  and  in  this  way 
may  be  explained  the  secretion  in  the  blood  of  large  quantities  of 
hydrochloric  acid.  But  though  the  occurrence  of  traces  of  free  hy- 
drochloric acid  in  the  alkaline  blood  is  not  denied,  it  does  not  foL 
low  that  the  hydrochloric  acid  passes  by  diffusion  from  the  blood 
to  the  gastric  juice.  Similar  processes  in  other  animal  glands 
render  it  probable  that  here,  as  in  other  cases  of  secretion,  we  have 
to  deal  with  a  yet  unexplained  specific  secretory  action  of  the 
glandular  cells.  The  process  going  on  in  the  secretion  of  hydro- 
chloric acid  is  not  yet  understood. 

After  an  abundant  meal,  when  the  store  of  pepsin  in  the  stom- 
ach is  completely  exhausted,  Schiff  claims  that  certain  bodies 
especially  dextrin,  have  the  propertv  of  causing  a  supply  of  pepsin 
in  the  mucous  membrane.     This  "charge  theory,"  though  experi- 


186  PHYSIOLOGICAL   CHEMISTRY. 

mentally  proved  by  several  investigators,  has  nevertheless  not  yet 
heen  confirmed.  On  the  contrary,  the  statement  of  Schife  that  a 
substance  forming  pepsin, a  '^pepsinogen"  or  " prop)epsin,"  occurs  in 
the  ventricle  has  been  proved.  Langlet  has  shown  positively  the 
existence  of  such  a  substance  in  the  mucous  coat.  This  substance, 
propepsin,  shows  a  comparatively  strong  resistance  to  dilute  alkalies 
(a  soda  solution  of  5  p.  m.)  which  easily  destroys  pepsin  (Lan'GLEy). 
Pepsin,  on  the  other  hand,  withstands  better  than  propepsin  the 
action  of  carbon  dioxide,  which  quickly  destroys  the  latter  (Lang- 
ley).  The  occurrence  of  a  rennet  zymogen  in  the  mucous  coat  has 
been  mentioned  above. 

The  question  in  which  cells  the  two  zymogens,  especially  the 
propepsin,  are  produced  has  been  extensively  discussed  for  several 
years.  Formerly  it  was  the  general  opinion  that  the  delomorphic 
cells  were  pepsin-cells,  but  at  the  present  time  the  theory  univer- 
sally prevails,  based  chiefly  on  the  experiments  of  Heidenhain" 
and  his  pupils,  supported  by  Langley  and  others,  that  the  forma- 
tion of  pepsin  goes  on  in  the  adelomorphic  or  principal  cells. 

The  Pyloric  Secretion.  That  part  of  the  pyloric  end  of  the 
dog's  stomach  which  contains  no  fundus  glands  was  dissected  by 
Klemensiewicz,  one  end  being  sewed  together  in  the  sliape  of  a 
blind  sack  and  the  other  sewed  into  the  stomach.  From  the  fistula 
thus  created  he  was  able  to  obtain  the  pyloric  secretion  of  a  living 
animal.  This  secretion  is  alkaline,  viscous,  jelly-like,  rich  in  mucin, 
of  a  specific  gravity  of  1.009-1.010,  and  containing  16.5-20.5 
p.  m.  solids.  It  has  no  effect  on  fat,  but  acts,  though  very  slowly, 
on  starch,  converting  it  into  sugar,  and  habitually  contains  pepsin 
in  rather  large  amounts.  Heidenhain  has  observed  the  same  in 
permanent  pyloric  fistula. 

The  secretion  of  the  juices  of  the  stomach  is  dependent  to  a 
great  extent  upon  the  excitement  acting  on  the  mucous  coat  of  the 
stomach,  and  it  follows  from  this  that  the  quantity  of  secretion 
under  different  conditions  must  vary  considerably.  The  statements 
of  the  quantity  of  gastric  juice  secreted  in  a  certain  time  are  there- 
fore so  unreliable  that  they  need  not  be  taken  into  account. 

The  Chyme  and  the  Digestion  in  the  Stomach.  By  the  move- 
ments of  the  walls  of  the  stomach  the  contents  are  kneaded  and  the 
food-particles  pressed  against  each  other  and  divided.     By  means  of 


DIGESTION.  187 

this  mechanical  irritation  of  the  mucous  coat  of  the  stomach,  as 
well  as  by  the  chemical  irritation  caused  by  the  food  and  saliva,  an 
increased  secretion  of  gastric  juice  occurs.  The  food  is  thereby 
freely  mixed  with  liquid  and  is  gradually  converted  into  a  pulpy 
mass,  the  chyme.  This  mass  is  acid  in  reaction,  and  with  the  ex- 
ception of  the  interior  of  large  pieces  of  meat  or  other  solid  foods, 
the  chyme  is  acid  throughout.  The  metabolism  products  in  the 
digestion  of  proteids  and  carbohydrates  may  always  be  detected  in 
the  chyme  ;  likewise  more  or  less  changed  undigested  residues  of 
swallowed  food,  which  indeed  form  the  chief  mass  of  the  consti- 
tuents of  the  chyme. 

In  the  chyme  morsels  of  flesh  more  or  less  changed  are  found 
which,  when  unboiled  flesh  is  partaken  of,  may  be  much  swollen 
and  slippery.  Muscle  and  caetilage  are  also  often  swollen  and 
slippery,  while  pieces  of  boxe  sometimes  show  a  rough  and  uneven 
surface  after  the  digestion  has  continued  for  some  time,  which  de- 
pends upon  the  fact  that  the  gelatinous  substances  of  the  bone  are 
attacked  more  quickly  by  the  gastric  juice  than  the  earthy  parts. 
Milk  coagulates  in  the  stomach  by  the  combined  action  of  the 
rennet  enzyme  and  the  acid,  but  in  certain  cases  by  the  action  of  the 
acid  alone.  From  the  relative  quantities  of  the  swallowed  milk  to 
the  other  food  either  large  and  solid  lumps  of  cheese  are  formed  or 
smaller  lumps  or  grains  which  are  divided  in  the  pulpy  mass.  Cow's 
milk  regularly  yields  large,  solid  masses  or  lumps;  human  milk 
gives,  on  the  contrary,  a  fine,  loose  coagulum  or  a  fine  precipitate 
which  is  immediately  dissolved  in  part  by  the  acid  liquid.  The 
milk-sugar  may  pass  into  lactic-acid  fermentation,  and  this  accord- 
ing to  EiCHET,  is  the  reason  why  the  acid  reaction  of  the  contents  of 
the  stomach  is  greater  at  the  end  of  the  digestion  of  a  meal  consist- 
ing mainly  of  milk. 

Bread,  especially  when  not  too  fresh,  is  converted  rather  easily 
into  a  pulpy  mass  in  the  stomach.  Other  vegetable  foods,  such  as 
POTATOES,  may,  if  not  sufficiently  masticated,  often  be  found  in  the 
contents  of  the  stomach,  very  little  changed,  several  hours  after  a 
meal. 

Starch  is  not  converted  into  sugar  by  the  gastric  juice,  but  in 
the  first  phases  of  the  digestion,  before  a  large  quantity  of  hydro- 
chloric acid  has  accumulated,  it  seems  that  the  action  of  the  saliva 


188  PHTSIOLOQICAL   CHEMISTRT, 

continues,  and  therefore  the  presence  of  dextrin  and  sugar  can  bt 
detected  in  the  contents  of  the  stomach.  Besides  this  the  car^ 
bohydrates  in  the  stomach  may  in  part  undergo  a  lactic-acid  fer< 
mentation,  probably  caused  by  the  micro-organisms  present. 

According  to  the  investigations  of  Ellenbekgek  and  Hoff- 
MEISTER  on  horses  and  pigs,  after  a  meal  rich  in  amylaceous  bodies 
in  the  first  phase  of  the  digestion,  an  amylolt&e  takes  place  with 
the  formation  of  lactic  acid ;  then  gastric  juice  containing  hydro- 
chloric acid  is  secreted,  then  follows  a  second  phase  in  which  the 
proteolyse  takes  place.  As  a  rule,  the  formation  of  lactic  acid  de- 
creases as  the  secretion  of  hydrochloric  acid  increases.  Ewald 
and  Boas  claim  that  a  similar  condition  also  exists  in  human 
beings.  They  claim  that  there  is  in  the  first  stage  of  digestion  a 
predominance  of  lactic  acid  in  the  stomach,  in  the  second  a  simul- 
taneous occurrence  of  lactic  and  hydrochloric  acids,  and  in  the  third 
stage  almost  exclusively  hydrochloric  acids.  Kjaergaaed  has 
lately  formed  the  same  conclusions  from  his  investigations  on 
children  and  robust  persons.  In  persons  with  altered  blood-vessels 
due  to  senility  the  contents  of  the  stomach  show  chiefly  the  presence 
of  lactic  acid.  Such  persons  digest  large  amounts  of  carbohydrates, 
while  the  digestion  of  albuminous  bodies  is  decreased. 

The  FATS  which  are  not  fluid  at  the  ordinary  temperature  melt 
in  the  stomach  at  the  temperature  of  the  body  and  become  fluid. 
In  the  same  way  the  fat  of  the  fatty  structure  is  set  free  in  the 
stomach  by  the  gastric  juice  which  digests  the  cell-membrane.  The 
gastric  juice  itself  seems  to  have  no  action  on  fats,  but,  according  to 
recent  statements,  a  splitting  of  the  neutral  fats  into  fatty  acids  and 
glycerin  takes  place,  though  not  to  a  great  extent.  This  splitting  is 
not  dependent  on  the  bacteria  of  the  contents  of  the  stomach,  or 
at  least  only  to  a  small  extent  (Klemperer  and  Scheurleis').  The 
soluble  salts  of  the  food  naturally  are  found  dissolved  in  the 
liquids  of  the  contents  of  the  stomach ;  but  the  insoluble  salts  may 
also  be  dissolved  by  the  acid  of  the  gastric  juice. 

Since  the  hydrochloric  acid  of  the  gastric  juice  prevents  the 
contents  of  the  stomach  from  fermenting  with  the  generation  of 
gas,  those  gases  which  occur  in  the  stomach  probably  depend,  at 
least  in  great  measure,  upon  the  swallowed  air  and  saliva,  and 
upon  those  gases  generated  in  the  intestines  and  returned  through 


DIGESTION.  18a 

the  pyloric  valve.  Plaker  found  in  the  stomach-gases  of  a  dog 
66-68^  N,  25-33^  COj,  and  only  a  small  quantity,  0.8-6. 1^  of 
oxygen. 

According  as  the  food  is  finely  or  coarsely  divided  it  passes 
sooner  or  later  through  the  pylorus  into  the  intestines.  From 
Busch's  observations  on  a  human  intestinal  fistula,  it  required 
generally  15-30  minutes  after  eating  for  undigested  food,  such 
as  pieces  of  meat,  to  pass  into  the  upper  part  of  the  intestines. 
Among  the  cases  of  duodenal  fistula  in  human  beings  observed  by 
KuHXE,  one  is  mentioned  in  which  he  saw,  ten  minutes  after  eat- 
ing, uncurdled  but  still  coagulable  milk  and  small  pieces  of  meat 
puss  out  of  the  fistula.  The  time  in  which  the  stomach  unburdens 
itself  of  its  contents  depends,  however,  upon  the  rapidity  with 
which  the  quantity  of  hydrochloric  acid  increases,  for  it  seems  to 
act  as  a  sort  of  irritant  and  causes  the  opening  of  the  pylorus 
(EwALD  and  others).  Many  other  conditions  also  come  into  play, 
namely,  the  activity  of  the  gastric  Juice,  the  quantity  and  character 
of  the  food,  etc.,  etc.,  and  therefore  the  time  required  to  empty  the 
stomach  must  be  variable.  Eichet  observed  in  a  case  of  stomach 
fistula  that  in  man  the  quantity  of  food  which  is  in  the  stomach 
the  first  three  hours  is  not  essentially  changed,  but  that  in  the 
course  of  a  quarter  of  an  hour  nearly  all  is  driven  out,  so  that  only 
a  small  residue  remains.  Kuhne  has  made  about  the  same  obser- 
vations on  dogs  and  human  beings.  He  found,  indeed,  in  dogs  that 
in  the  first  hour  small  quantities  of  meat  passed  into  tlie  intestines 
every  ten  minutes  ;  but  he  also  observed  that  in  dogs,  on  an  ave- 
rage, about  five  hours  after  eating,  in  man  somewhat  earlier,  a  free 
emptying  into  the  intestines  takes  place.  According  to  other 
investigators  (Ewald  and  Boas),  the  emptying  of  the  human 
stomach  does  not  take  place  suddenly,  but  gradually.  Beaumont 
found  in  his  extensive  observations  on  the  Canadian  hunter,  St. 
Martin,  that  the  stomach,  as  a  rule,  is  emptied  1^-5^  hours  after 
a  meal,  depending  upon  the  character  of  the  food. 

The  time  in  which  different  foods  leave  the  stomach  depends 
upon  their  digestibility.  In  regard  to  the  unequal  digestibility  in 
the  stomach  of  foods  rich  in  proteids,  which  really  form  the  object 
of  the  action  of  the  gastric  juice,  a  distinction  must  be  made  be- 
tween  the  rapidity  with  which   the  proteids  are  converted  into 


190  PHTSIOLOOIGAL   CHEMISTRY. 

albumoses  and  peptones  and  the  rapidity  with  which  the  food  is 
converted  into  chyme,  or  at  least  so  prepared  that  it  may  easily 
pass  into  the  intestines.  This  distinction  is  especially  important 
from  a  practical  standpoint.  When  a  proper  food  is  to  be  decided, 
upon  in  cases  of  diminished  stomachic  digestion,  it  is  important  to 
select  such  foods  as,  independent  of  the  difficulty  or  ease  with 
which  their  proteid  is  peptonized,  leave  the  stomach  easily  and 
quickly,  and  which  require  as  little  action  as  possible  on  the  part 
of  this  organ.  From  this  point  of  view  those  foods,  as  a  rule,  are 
most  digestible  which  are  fluid  from  the  start  or  rnay  be  easily 
liquefied  in  the  stomach;  but  these  foods  are  not  always  the  most 
digestible  in  the  sense  that  their  proteid  is  most  easily  peptonized. 
As  an  example,  hard-boiled  white  of  egg  is  more  easily  peptonized 
than  fluid  white  of  egg  at  a  degree  of  acidity  of  1-2  p.  m.  HCl ; 
nevertheless  we  consider,  and  justly,  that  an  unboiled  or  soft-boiled 
egg  is  easier  to  digest  than  a  hard-boiled  one.  Likewise  uncooked 
meat,  when  it  is  not  chopped  very  fine,  is  not  more  quickly  but 
more  slowly  peptonized  by  the  gastric  juice  than  the  cooked,  but  if 
it  is  divided  sufficiently  fine  it  is  often  more  quickly  peptonized 
than  the  cooked. 

The  greater  or  less  facility  with  which  the  different  albuminous 
foods  are  peptonized  by  the  gastric  juice  has  been  comparatively 
little  studied,  and  as  the  conditions  in  the  stomach  are  more  com- 
plicated, results  obtained  with  artificial  gastric  juice  are  often  of 
no  value  for  the  practising  physician  and  should  in  any  case  be 
used  only  with  the  greatest  caution.  Under  these  circumstances 
we  cannot  enter  more  deeply  into  this  subject,  but  the  reader  is 
referred  to  text-books  on  dietetics  and  the  theory  of  foods. 

As  our  knowledge  of  the  digestibility  of  the  different  foods  in 
the  stomach  is  slight  and  dubious  so  also  our  knowledge  of  the 
action  of  other  bodies,  such  as  alcoholic  drinks,  bitter  principles, 
spices,  etc.,  on  the  natural  digestion  is  very  uncertain  and  imper- 
fect. The  difficulties  which  stand  in  the  way  of  this  kind,  of  in- 
vestigation are  very  great,  and  therefore  the  results  obtained  thus 
far  are  often  ambiguous  or  conflict  with  each  other.  For  example, 
one  investigator  has  seen  that  small  quantities  of  alcohol  or  alcoholic 
drinks  do  not  prevent  but  rather  facilitate  digestion  ;  others 
observe  only  a  preventive  action  ;  while  other  investigators  believe 


DIOE8TI0N.  191 

to  have  found  that  the  alcohol  first  acts  somewhat  as  a  preventive, 
but  afterwards,  as  a  rule,  it  is  absorbed,  producing  an  abundant 
secretion  of  gastric  juice,  and  thereby  facilitating  digestion  (Cl. 
Bernard,  Gluzinski,  Chittenden). 

The  digestion  of  sundry  foods  is  not  dependent  on  one  organ 
alone,  but  divided  among  several.     For  this  reason  it  is  to  be  ex- 
pected that  the  various  digestive  organs  can  act  for  one  another 
to  a  certain  point,  and  that  therefore   the  work  of   the  stomach 
could  be  taken  up  more  or  less  by  the  intestines.     This  in  fact  is 
the  case.     Thus  the  stomach  of  a  dog  has  been  almost  completely 
extirpated  (Czerny),  and  even  that  part  necessary  in  the  digestive 
process  has  been  eliminated  by  plugging  the  pyloric  opening  (LuD- 
wiG  and  Ogata),  and  in  both  cases  it  was  possible  to  keep   the 
animal  alive,  well  fed,  and  strong.     In  these  cases  it  is  evident  that 
the  digestive  work  of  the  stomach  was  taken  up  by  the  intestines. 
That  the  stomach  nevertheless,  during  normal  conditions,  bears  an 
essential  part  of  the  process  of  digestion  may  be  inferred  from  the 
fact  that  the  products  of  the  proteolyse  can  generally  be  detected 
in  the  contents  of  the  human  stomach  even  shortly  after  a  meal.    By 
tests  on  dogs  that  had  been  given  meat-powder,  Cahn  found  large 
quantities  of  peptone  in  the  stomach,  and  this  absorption,  as  shown 
by  ScHMiDT-MtJLHEiM,  requires  about  the  same  steps  as  digestion. 
It  is  meanwhile  quite  generally  assumed  that  no  peptonization 
of  the  proteids  worth  mentioning  occurs  in  the  stomach,  and  that 
the  albuminous  foods  are  only  prepared  in  the  stomach  for  the  real 
digestive  processes  in  the  intestines.     That  the  stomach  serves  in 
the  first  place  as  a  storeroom  follows  from  its  shape,  and  this  func- 
tion is  of  special  value  in  certain  new-born  animals,  for  instance  in 
dogs  and  cats.     In  these  animals  the  secretion  of  the  stomach  con- 
tains only  hydrochloric  acid  but  no  pepsin,  and  the  casein  of  the 
milk   is   converted  by   the  acid  alone  into  solid  lumps  or  a  solid 
coagulum  which  fills  the  stomach.    Small  portions  of  this  coagulum 
pass  into  the  intestines  only  little  by  little  and  an  overburdening  of 
the  intestines  is  thus  prevented.     In  other  animals,  such  as  the  snake 
and  certain  fishes,  which  swallow  their  food  entire,  it  is  certain  that 
the  major  part  of  the  process  of  digestion  takes  place  in  the  stomach. 
The  importance  of  the  stomach  in  digestion  cannot  at  once  be  de- 
cided.    It  varies  for  different  animals,  and  it  may  vary  in  the  same 
animal,   depending   upon   the   division   of  the   food,   the  rapidity 


192  PHT8I0L00ICAL   CHEMISTRT. 

with  which  the  peptonization  takes  place,  the  more  or  less  rapid 
increase  in  the  amount  of  hydrochloric  acid,  and  so  on. 

It  is  a  well-known  fact  that  the  contents  of  the  stomach  may 
be  kept  without  decomposing  for  some  time  by  means  of  hydro- 
chloric acid,  while,  on  the  contrary,  when  the  acid  is  neutralized  a 
fermentation  commences  by  which  lactic  acid  and  other  organic 
acids  are  formed.  The  hydrochloric  acid  of  the  gastric  juice  has 
unquestionably  an  anti-fermentive  action,  and  also,  like  dilute 
mineral  acids,  an  antiseptic  action.  This  action  is  of  importance, 
as  many  disease  micro-organisms  may  be  destroyed  by  the  gastric 
juice.  The  bacillus  of  cholera  is  killed  by  the  normal  acid  gastric 
juice,  while  if  it  is  introduced  into  the  stomach  after  an  injection 
of  a  soda  solution  it  may  remain  active  (Koch,  Nicati  and 
Kietsch).  Also  varieties  of  streptococcus  infecting  wounds  and 
the  staphylococcus  pyog.  aureus  are  killed  by  the  acid  gastric  juice 
(Alapy).  Still  the  gastric  juice  does  not  act  on  all  micro-organisms, 
and  especially  in  the  state  of  spores  they  can  withstand  its  action. 
As  an  example,  the  tubercle-virus  is  not  destroyed  by  the  gastric 
juice  (Falk),  and  the  spores  of  the  anthrax  bacteria  do  not  seem 
to  be  always  destroyed  by  the  hydrochloric  acid  of  the  gastric  juice. 

After  death,  if  the  stomach  still  contains  food,  digestion  goes 
on  of  itself  not  only  in  the  stomach  but  also  in  the  neighboring 
organs  during  the  slow  cooling  of  the  body.  This  leads  to  the 
question,  why  does  the  stomach  not  digest  itself  during  life? 
Ever  since  Pavt  has  shown  that  after  tying  the  smaller  blood- 
vessels of  the  stomach  of  dogs  the  corresponding  part  of  the 
mucous  membrane  was  digested,  efforts  have  been  made  to  find  the 
cause  in  the  neutralization  of  the  acid  of  the  gastric  juice  by  the 
alkali  of  the  blood.  That  the  reason  for  the  non-digestion  during 
life  is  to  be  sought  for  in  the  normal  circulation  of  the  blood  cannot 
be  contradicted;  it  is  more  probably  found  in  the  fact  that  the 
living  mucous  coat  nourished  by  the  alkaline  blood  shows  quite 
different  absorption,  diffusion,  and  filtration  properties  than  the 
dead  mucous  coat.  This  last  was  shown  long  ago  by  Ranke  and 
Halenke. 

Under  pathological  conditions  irregularities  in  the  secretion  as 
well  as  in  the  absorption  and  in  the  mechanical  work  of  the 
stomach   may  occur.      Pepsin   is  almost  always  present,  but  the 


DIGESTION.  193 

absence  of  the  rennet  enzyme,  as  above  stated,  may  occur  in  many 
cases  (Boas,  Johnson,  Klempeker).  In  regard  to  the  acid,  it 
should  be  mentioned  that  sometimes  this  secretion  may  be  in- 
creased so  that  an  abnormally  acid  gastric  juice  is  secreted,  and 
sometimes  may  be  decreased  so  that  little  or  hardly  any  hydro- 
chloric acid  is  secreted.  A  hypersecretion  of  acid  gastric  juice 
sometimes  occurs.  In  the  secretion  of  too  little  hydrochloric  acid 
the  same  conditions  appear  as  after  the  neutralization  of  the  acid 
contents  of  the  stomach  outside  of  the  organism.  Fermentation 
processes  now  appear  in  which,  besides  lactic  acid,  there  appear  also 
volatile  fatty  acids,  such  as  butyric  and  acetic  acids,  etc.,  and  gases 
like  hydrogen.  These  fermentation  products  are  therefore  often 
found  in  the  stomach  in  cases  of  chronic  catarrh  of  the  stomach, 
which  may  give  rise  to  belching,  heart-burn,  and  other  symptoms. 
Among  the  foreign  substances  found  in  the  contents  of  the 
stomach  we  have  urea,  or  ammonium  carbonate  derived  there- 
from in  uraemia;  blood,  which  generally  forms  a  dark-brown  mass 
through  the  presence  of  hsematin,  due  to  the  action  of  the  gastric 
juice  ;  bile,  which,  especially  during  vomiting,  easily  finds  its  way 
through  the  pylorus  into  the  stomach,  but  whose  presence  seems  to 
be  without  importance. 

If  it  is  desired  to  test  the  gastric  juice  or  the  contents  of  the 
stomach  for  pepsin,  fibrin  may  be  employed.  If  this  is  thoroughly 
washed  immediately  after  beating  the  blood,  well  pressed  and 
placed  in  glycerin,  it  may  be  kept  in  serviceable  condition  an  inde- 
finitely longtime.  The  gastric  juice  or  the  matter  contained  in  the 
stomach — the  latter,  if  necessary,  having  been  previously  diluted 
with  1  p.  m,  hydrochloric  acid,  is  filtered  and  tested  with  fibrin  at 
ordinary  temperature.  (It  must  not  be  forgotten  that  a  control  test 
must  be  made  with  acid  alone  and  another  porton  of  the  same 
fibrin.)  If  the  fibrin  is  not  noticeably  digested  within  one  or  two 
hours,  no  pepsin  is  present,  or  at  most  there  are  only  slight  traces. 

In  testing  for  rennet  enzyme  the  liquid  must  be  first  carefully 
neutralized.  To  10  cc.  unboiled  amphoteric  (not  acid)  reacting 
cow's  milk  add  1-2  cc.  of  the  filtered  neutralized  liquid;  but  care 
must  be  taken  not  to  add  too  much  of  the  liquid  from  the  stomach, 
for  the  coagulation  may  be  retarded  or  prevented  by  diluting  the 
milk.  In  the  presence  of  rennet  the  milk  should  coagulate  to  a 
solid  mass  at  the  temperature  of  the  body  in  the  course  of  10-20 
minutes  without  changing  its  reaction.  If  the  milk  is  diluted  too 
much  by  the  addition  of  the  liquid  of  the  stomach,  only  coarse 


194  PHTSIOLOOICAL  CHEMI8TBT. 

flakes  are  obtained  and  no  solid  coagulum.  Addition  of  lime  salts 
is  to  be  avoided,  as  they  in  great  excess  may  produce  a  partial 
coagulation  even  in  the  absence  of  rennet. 

In  many  cases  it  is  especially  important  to  determine  the 
degree  of  acidity  of  the  gastric  juice.  This  may  be  done  by  the 
ordinary  titration  methods.  Phenol  phthalein  must  not  be  used  as 
an  indicator,  for  we  get  too  high  results  in  the  presence  of  large 
quantities  of  albumin.  Good  results  may  be  obtained,  on  the  con- 
trary, by  using  very  delicate  litmus-paper.  As  the  acid  reaction  of 
the  contents  of  the  stomach  may  be  caused  simultaneously  by 
several  acids,  still  the  degree  of  acidity  is  here,  as  in  other  cases 
expressed  in  only  one  acid,  e.  g.,  HOI.     Generally  the  acidity  is 

N 
expressed  by  the  number  of  cc.  of  y^  caustic  soda  which  is  required 

to  neutralize  the  several  acids  in  100  cc.  of  the  liquid  of  the  stomach. 

An  acidity  of  43^  means  that  100  cc.  of  the  liquid  of  the  stomach 

N 
required  43  cc.  of  —  caustic  soda  to  neutralize  it. 

It  is  also  important  to  be  able  to  ascertain  the  nature  of  the  acid 
or  acids  occurring  in  the  contents  of  the  stomach.  For  this  pur- 
pose, and  especially  for  the  detection  of  free  hydrochloric  acid,  a  great 
number  of  color  reactions  have  been  proposed,  which  are  all  based 
upon  the  fact  that  the  coloring  substance  gives  a  characteristic 
color  with  very  small  quantities  of  hydrochloric  acid,  while  lactic 
acid  and  the  other  organic  acids  do  not  give  these  colorations,  or 
only  in  a  certain  concentration,  which  can  hardly  exist  in  the  con- 
tents of  the  stomach.  These  reagents  are  a  mixture  of  ferric 
ACETATE  and  POTASSIUM  SULPHOCYANIDE  solution  (Mohr's  re- 
agent  is   modified    by   several    investigators),  methtl,    anilin- 

VIOLET,    TROP^OLIN"    00,      CONGO     RED,    MALACHITE-GREEN,   PHLO- 

ROGLUCIN-VANILLIN,  BENzopuRPURiN"  6  B,  and  others.  As 
reagents  for  free  lactic  acid  Uffelmann  suggests  a  strongly 
diluted,  amethyst-blue  solution  of  ferric  chloride  and  carbolic 
ACID  or  a  strongly  diluted,  nearly  colorless  solution  of  ferric 
chloride.  These  give  a  yellow  with  lactic  acid,  but  not  with 
hydrochloric  acid  or  with  volatile  fatty  acids. 

The  value  of  these  reagents  in  testing  for  free  hydrochloric  acid 
or  lactic  acid  is  still  disputed.  Among  the  reagents  for  free  hydro- 
chloric acid,  Mohr's  test  (even  though  not  very  delicate),  GuNZ- 
BURG^S  test  with  phloroglucin-vanillin,  and  the  test  with  tro- 
pgeolin  00,  performed  in  moderate  heat  as  suggested  by  Boas,  seem 
to  be  the  most  valuable.  If  these  tests  give  positive  results,  then  the 
presence  of  hydrochloric  acid  may  be  considered  as  proved.  A 
negative  result  does  not  eliminate  the  presence  of  hydrochloric  acid, 
as  the  delicacy  of  these  reactions  has  a  limit,  and  also  the  simul- 


DIGESTION.  196 

taueous  presence  of  albumin,  peptones  and  other  bodies  influence  the 
reactions  more  or  less.  The  reactions  for  lactic  acid  may  also  give 
negative  results  in  the  presence  of  comparatively  large  quantities  of 
hydrochloric  acid  in  the  liquid  to  be  tested.  Sugar  and  other  bodies 
(Fr.  MiJLLER)  may  act  with  these  reagents  similarly  to  lactic  acid. 

As  the  above-mentioned  reactions  for  hydrochloric  acid  and 
organic  acids  are  not  claimed  to  be  sufficient  in  exact  investigations, 
while  they  may  serve  in  many  cases  for  clinical  purposes,  it  will 
suffice  to  refer  the  reader  to  other  text-books  and  especially  to 
"  Klinisclie  Diagnostik  innerer  Kt'atikheiten,"  by  R.  v.  Jaksch, 
2d  edition,  1889,  for  the  performance  and  the  relative  value  of 
these  tests. 

The  method  suggested  by  Cahn  and  v.  Mehring  for  the 
detection  and  simultaneous  quantitative  estimation  of  hydrochloric 
acid  in  the  presence  of  lactic  acid  and  volatile  fatty  acids  in  the 
€ontents  of  the  stomach  will  be  here  given.  The  chief  points 
are  the  following:  First  the  volatile  acids  are  distilled  and  their 
quantity  determined  in  the  distillate  by  titration.  The  lactic  acid 
is  removed  from  the  liquid  remaining  in  the  retort  by  repeated 
shaking  with  large  quantities  of  ether,  and  after  the  evaporation 
of  the  ether  the  quantity  of  lactic  acid  in  the  residue  is  deter- 
mined by  titration.  The  liquid  which  has  been  shaken  out  with 
the  ether  is  either  directly  titrated  for  hydrochloric  -acid,  or,  as 
suggested  by  Rabuteau,  combines  the  hydrochloric  acid  with  cin- 
chonin  by  digestion  therewith  at  a  gentle  heat  until  the  reaction 
is  neutral.  The  cinchonin  combination  is  then  agitated  with 
chloroform  and  the  chloroform  evaporated,  and  fiom  the  amount 
of  chlorine  in  this  residue  we  may  calculate  the  quantity  of  pre- 
viously -  free  hydrochloric  acid.  This  somewhat  expensive  and 
lengthy  method  is  still  not  free  from  errors,  and  it  is  made  useless 
by  that  following. 

The  method  of  K.  Morner  and  Sjoqvist  depends  on  the  fol- 
lowing principle  :  When  the  gastric  juice  is  evaporated  to  dryness 
with  barium  carbonate  and  then  calcined  the  organic  acids  burn  up 
and  give  insoluble  barium  carbonate,  while  the  hydrochloric  acid 
forms  soluble  barium  chloride.  From  the  quantity  of  this  the 
original  amount  of  hydrochloric  acid  can  be  calculated.  10  cc. 
of  the  filtered  contents  of  the  stomach  is  mixed  in  a  small  platinum 
or  silver  dish,  by  means  of  a  clean,  sharp  knife-point,  with  the 
barium  carbonate  free  from  chlorides,  and  evaporated  to  dryness. 
The  residue  is  burnt  and  allowed  to  glow  for  a  few  minutes.  The 
cooled  carbon  is  gently  rubbed  with  water  and  completely  extracted 
with  boiling  water,  and  the  filtrate  (about  50  cc.)  treated  with  an 
equal  volume  of  alcohol  and  3-4  cc.  sodium  acetate  solution  (10.^ 
acetic  acid  and  lOfo  acetate).  The  amount  of  barium  in  the  filtrate 
is  determined  by  titration  with  a  solution  of  potassium  bichromate, 


196  PRT8I0L0QIGAL  CHEMISTRY. 

in  which  the  alcohol  facilitates  the  precipitation  of  the  barium 
chromate,  while  the  acetate  prevents  in  part  the  precipitation  of 
the  calcium  carbonate  and  in  part  the  setting  free  of  hydrochloric 
acid.  The  potassium-bichromate  solution  should  contain  about 
8.5  grms.  potassium  dichromate  to  the  litre.     Its  titre  must  exactly 

correspond  with  an  —  barium-chloride  solution,  and  the  procedure 

is  the  same  as  in  the  titration  of  the  BaCl2  solution  obtained  from 
the  contents  of  the  stomach.  A  paper  moistened  with  tetramethyl- 
paraphenylendiamin  is  used  as  indicator;  this  is  colored  blue  by  a 
bichromate  in  acetic-acid  solution.  In  titrating  we  add  chromate 
solution  as  long  as  the  barium  chromate  precipitated  does  not  ap- 
parently increase,  then  test  with  the  indicator  paper  after  each  addi- 
tion until  it  gives  a  decided  blue  coloration  within  one  minute,  and 
stop  adding  chromate  solution.    As  the  titre  of  the  chromate  solution 

N 
has  been  determined  by  an  —  BaCl2  solution,  it  is  easy  to  calculate 

the  quantity  of  HCl  in  10  cc.  of  the  gastric  juice  corresponding  to 
the  number  of  cc.  of  the  chromate  solution  used.  If  the  total 
acidity  is  determined  in  a  second  portion  of  the  gastric  juice,  then 
the  quantity  of  lactic  acid  or  other  organic  acids  represented  as 
HCl  may  b.e  calculated.  This  method,  which  is  the  most  exact 
known  at  present,  gives  not  only  the  amount  of  free  hydrochloric 
acid,  but  also  the  hydrochloric  acid  combined  with,  the  albumin 
and  peptone. 

In  testing  for  volatile  fatty  acids  the  contents  of  the  stomach 
should  not  be  directly  distilled,  as  volatile  fatty  acids  may  be 
formed  by  the  decomposition  of  other  bodies,  such  as  albumin  and 
haemoglobin.  The  neutralized  contents  of  the  stomach  are  there- 
fore precipitated  with  alcohol  at  ordinary  temperature,  filtered 
quickly,  pressed,  and  repeatedly  extracted  by  alcohol.  The 
alcoholic  extracts  are  made  faintly  alkaline  by  soda,  and  the  alcohol 
distilled.  The  residue  is  now  acidified  by  sulphuric  or  phosphoric 
acid  and  distilled.  The  distillate  is  neutralized  by  soda  and  evapo- 
rated to  dryness  on  the  water-bath.  The  residue  is  extracted  with 
absolute  alcohol,  filtered,  the  alcohol  distilled  off,  and  this  residue 
dissolved  in  a  little  water.  This  solution  may  be  directly  tested 
for  acetic  acid  with  sulphuric  acid  and  alcohol  or  with  ferric  chlo- 
ride. Formic  acid  may  be  tested  for  by  silver  nitrate,  which 
quickly  gives  a  black  precipitate;  and  butyric  acid  is  detected  by 
the  odor  after  the  addition  of  an  acid.  In  regard  to  the  methods 
for  more  fully  investigating  the  different  volatile  fatty  acids,  the 
reader  is  referred  to  other  text-books. 


DIGESTION.  197 


III.    The  Glands  of  the  Mucous  Membrane  of  the  Intes- 
tines and  their  Secretions. 

The  Secretion  of  Brunner's  Glands.  These  glands  are  partly 
considered  as  small  pancreas  glands  and  partly  as  mucous  or 
salivary  glands,  but  according  to  Grutzner  they  are  related  to  the 
pyloric  iglands.  They  are  assumed  to  contain  pepsin  (Grutzner 
and  diastatic  enzymes  (Costa,  Budge  and  Krolow).  The  diffi- 
culty of  collecting  the  secretions  of  these  glands  free  from  contami- 
nation, however,  makes  these  assumptions  somewhat  unreliable. 

The  Secretion  of  Lieberkuhn's  Glands.  The  secretion  of  these 
glands  has  been  studied  by  the  aid  of  a  fistula  in  the  intestines 
according  to  the  method  of  Thirt  and  Yella.  Very  little  if  any 
secretion  takes  peace  in  fasting  animals  (dog)  when  the  mucous 
membrane  is  not  irritated.  The  secretion  begins  in  the  first  hour 
after  partaking  of  food,  but  the  maximum  varies  with  the  quantity 
and  character  of  the  food  (Heidexhaix).  Mechanical,  chemical, 
or  electrical  irritation  excites  a  secretion  or  increases  that  already 
begun  (Thirt).  Laxatives  do  not  increase  the  secretion,  while 
pilocarpin  produces  a  very  abundant  one  (Masloff  and  Vella). 
The  quantity  of  this  secretion  in  the  course  of  24  hours  has  not 
been  exactly  determined. 

In  the  upper  part  of  the  small  intestines  of  the  dog  this  secre- 
tion is  scanty,  slimy,  and  gelatinous;  in  the  lower  part  it  is  more 
fluid,  -with  gelatinous  lumps  or  flakes  (Kohmann").  Intestinal 
jnice  has  a  strong  alkaline  reaction,  generates  carbon  dioxide  on 
the  addition  of  an  acid,  and  contains  (in  dogs)  nearly  a  constant 
quantity  of  XaCl  and  !N"a.2C03,  4.8-5  and  4.5  p.  m.  respectively 
(GuMiLEWSKi,  R6hman"x).  It  Contains  albumina  (Thirt  found 
8.01  p.  m.),  the  quantity  decreasing  with  the  duration  of  the  elimi- 
nation. The  quantity  of  solids  varies.  In  dogs  the  quantity  of 
solids  is  12.2-24. 1  p.  m.,  and  in  sheep  46-47  p.  m.  The  specific 
gravity  of  the  intestinal  juice  of  the  dog,  according  to  the  observa- 
tions of  Thirt,  is  1.010-1.0107. 

The  action  of  intestinal  juice  has  not  been  exhaustively  studied 
and  the  opinions  concerning  it  are  somewhat  at  variance.  According 
to  most  investigators,  darch  is  converted  into  sugar,  a  statement 


198  PHYSIOLOGICAL   CEEMI8TBT. 

which  has  lately  been  confirmed  by  Bastianelli.  Intestinal  juice 
or  an  infusion  of  the  mucous  coat  inverts  cane-sugar  (Paschutik, 
Bastianelli),  and  this  inversion  is,  according  to  Beowk  and 
Heron,  produced  even  more  quickly  by  the  mucous  membrane 
itself.  Maltose  seems  to  be  quickly  changed  into  ghicose,  and  this 
action  depends  especially  on  Peter's  group  of  glands.  The  action: 
on  carbohydrates  takes  place  more  quickly  and  in  greater  quantity 
in  the  upper  part  of  the  intestine,  and  correspondingly  the  absorp- 
tion of  starch  and  sugar  occurs  more  quickly  in  the  upper  part 
than  in  the  lower  section  of  the  intestine  (Lanhois  and  Lepiite, 
Eohmann). 

Intestinal  juice  does  not  split  neutral  fats,  but  it  has  th& 
property,  like  other  alkaline  fluids,  of  emulsifying  the  fats.  In 
regard  to  its  action  on  albuminous  bodies  most  investigators  agree 
that  the  intestinal  juice  has  no  action  on  boiled  albumin  or  flesh, 
while  it  dissolves  fibrin  according  to  Thiry.  Albumoses  are  not 
converted  into  peptones  (Wenz,  Bastianelli).  Contrary  to  other 
investigators,  Schiff  claims  that  the  juice  from  a  successful  fistular 
operation  digests  not  only  coagulated  albumin  and  lumps  of  casein, 
but  also  unboiled  and  boiled  flesh.  The  lack  of  action  on  albumins, 
which  was  observed  by  other  investigators,  Schiff  attributes  to  the 
abnormal  juice  with  which  they  experimented.  Schiff  also  ob- 
tained from  an  operation  not  entirely  successful  a  juice  whose 
action  on  albumin  and  meat  was  no  greater  than  that  studied  by 
Thiry  and  other  investigators. 

Human  intestinal  juice  in  a  case  of  anus  prceternaturalis 
has  been  investigated  by  Demant.  This  juice  showed  itself  entirely 
inactive  on  albuminous  bodies,  even  on  fibrin  and  on  fats.  It  only 
showed  a  very  faint  action  on  boiled  starch.  Those  tests  on  the 
action  of  the  intestinal  juice  which  are  made,  in  isolated  stoppage 
of  the  intestine  in  animals  or  human  intestine  in  cases  of  anus 
prceternaturalis,  on  the  food  which  has  been  introduced  into  the  in- 
testine, generally  give  no  positive  results,  because  of  the  putrefac- 
tion processes  going  on  in  the  intestine. 

The  secretion  of  the  glands  in  the  large  intestine  seems  to  con- 
sist chiefly  of  mucus.  Fistulas  have  also  been  introduced  into 
these  parts  of  the  intestine,  which  are  chiefly  if  not  entirely  to  be 
considered  as  absorption  organs.  The  investigations  on  the  action  of 


DIGESTION.  199 

this  secretion   on  nutritive   bodies   liave   not   as  yet  yielded   any 
positive  results. 


IV.    Pancreas  Gland  and  Pancreatic  Juice. 

In  invertebrata,  which  have  no  pepsin  digestion  and  which  also 
have  no  formation  of  bile,  the  pancreas,  or  at  least  an  analogous 
organ,  seems  to  be  the  essential  digestion  gland.  On  the  contrary,  an 
anatomically  characteristic  pancreas  is  absent  in  certain  vertebrata 
and  in  certain  fishes.  Those  functions  which  should  be  performed 
by  this  organ  seem  to  be  performed  in  these  animals  by  the  liver, 
which  may  be  rightly  called  hepatopancreas.  In  man  and  in  most 
vertebrata  the  formation  of  bile  and  of  certain  secretions  containing 
enzymes  important  for  digestion  is  divided  between  the  two  organs, 
the  liver  and  the  pancreas. 

The  pancreas  gland  is  similar  in  certain  respects  to  the  parotid 
gland.  The  elements  secreted  by  the  former  consist  of  nucleated 
cells  whose  basis  forms  a  mass  rich  in  albumin,  expand  in  water 
and  in  which  two  distinct  zones  exist.  The  outer  zone  is  more 
homogeneous,  the  inner  cloudy  due  to  a  quantity  of  granular 
substance.  The  nucleus  lies  about  midway  between  the  two  zones, 
but  this  position  may  change  with  the  varying  relative  size  of  the 
two  zones.  According  to  HEiDENHAiaSr,  the  inner  part  of  the  cells 
diminishes  in  size  during  the  first  stages  of  digestion,  in  which  the 
secretion  is  active,  while  at  the  same  time  the  outer  zone  enlarges 
owing  to  the  absorption  of  new  material.  In  a  later  stage,  when 
the  secretion  has  decreased  and  the  absorption  of  the  nutritive 
bodies  has  taken  place,  the  inner  zone  enlarges  at  the  expense  of 
the  outer,  the  substance  of  the  latter  having  been  converted  into 
that  of  the  former.  Under  physiological  conditions  the  glands  are 
undergoing  a  constant  change,  at  one  time  consuming  from  the 
inner  part  and  at  another  time  growing  from  the  outer  part.  The 
inner  granular  zone  is  converted  into  the  secretion,  and  the  outer, 
more  homogeneous  zone,  which  contains  the  repairing  material,  is 
then  converted  into  the  granular  substance. 

Besides  considerable  quantities  of  proteids,  globulin,  nucleo- 
albumin,  and  alhumin,  we  find  in  this  gland  three  enzymes,  or. 


200  PHYSIOLOOICAL   CHEMI8TBT. 

more  correctly,  three  zymogens,  which  will  be  described  later.  We 
also  find  in  this  gland  nuclein,  leucin  (butalanin),  tyrosin  (not  in 
the  perfectly  fresh  gland),  xanthin,  1-8  p.  m.,  hypoxanthin,  3-4 
J),  m.,  guanin,  2-7.5  p.  m.  (all  figures  are  calculated  for  the  dried 
substance,  Kossel),  adenin,  inosit,  lactic  acid,  volatile  fatty  acids, 
fats,  and  mineral  substances.  According  to  the  investigations  of 
OiDTHiAN,  the  human  pancreas  contains  750-760  p.  m.  water,  240- 
250  p.  m.  organic  and  3.7-9.5  p.  m.  inorganic  substances. 

Pancreatic  Juice.  This  secretion  may  be  obtained  by  adjusting 
a  fistula  in  the  excretory  duct,  according  to  the  methods  suggested 
by  Bernard,  Ludwig,  and  Heidenhain.  If  the  operation  is 
performed  with  sufiicient  rapidity  and  dexterity  on  an  animal  which 
has  been  well  fed  a  few  hours  before,  there  is  obtained  from  the 
fistula,  as  a  rule,  immediately  after  the  operation  (te^nporary 
fistula)  a  secretion  rich  in  solids,  viscid,  very  active,  and  which  may 
be  considered  as  normal  pancreatic  juice.  Ordinarily,  however,  the 
gland  becomes  diseased  in  a  few  hours  or  days  after  the  operation, 
and  the  secretion  which  then  flows  out  of  the  fistula  {permanent 
fistula)  is  more  liquid,  deficient  in  solids,  and  in  certain  other 
respects  different  from  the  secretion  obtained  immediately  after  the 
operation.  Still  a  permanent  fistula  may  also  sometimes  yield  a 
normal  secretion  for  a  long  time  (Heidenhain),  while  the  tem- 
porary fistula  in  careless  operations  may  give  no  secretion  or  only 
an  abnormal  juice. 

In  herbivora,  such  as  rabbits,  whose  digestion  is  uninterrupted, 
the  secretion  of  the  pancreatic  juice  is  continuous.  In  carnivora  it 
seems,  on  the  contrary,  to  be  intermittent  and  dependent  on  the 
digestion.  During  starvation  the  secretion  almost  stops,  but  com- 
mences again  after  partaking  of  food.  Food  seems  to  act  in  a  two- 
fold manner.  First,  it  may,  with  the  more  abundant  flow  of  blood 
during  the  digestion,  which  is  seen  by  the  red  color  of  the  gland, 
convey  a  larger  quantity  of  nutritive  material  to  the  gland,  and 
thereby  cause  the  secretion  of  a  juice  rich  in  solid  nutritive  bodies. 
In  another  way  the  food  may  also,  by  the  irritation  which  it  pro- 
duces on  the  mucous  coat  of  the  stomach  and  the  duodenum,  cause 
an  increased  secretion.  That  the  food  indeed  acts  in  these  two 
ways  follows  from  the  fact  that  other  substances,  such  as  ether, 
may  also  cause  a  secretion  of  pancreatic  juice,  but  by  this  means 


DIGESTION.  201 

in  starvation  a  thin  fluid  is  secreted,  and  after  partaking  of 
food  a  tliick  fluid  is  produced.  According  to  the  observations 
of  Berxsteix,  Heidexhaix,  and  others,  the  secretion  increases 
rapidly  after  eating,  and  it  readies  its  maximum  in  the  course  of 
the  first  three  hours.  From  this  time  the  secretion  diminishes,  but 
may  again  increase  from  the  oth-Tth  hour,  when  generally  large 
quantities  of  food  pass  from  the  stomach  to  the  intestine.  Then 
it  again  decreases  continuously  from  the  9th-llth  hour,  and  stops 
entirely  at  the  15th-16th  hour. 

The  statements  as  to  the  amount  of  pancreatic  juice  secreted 
in  the  course  of  2-1  hours  are  variable  and  not  trustworthy. 
It  seems  positively  proved  that  the  permanent  fistula  yields  a  con- 
siderably larger  quantity  of  secretion  than  the  temporary.  While 
Keferstein"  and  Hallwachs,  and  Schmidt  and  Kroger,  find  that 
the  quantity  of  juice  secreted  from  the  first  is  45-100  grms.  per 
kilo  during  24  hours,  Bidder  and  Schmidt  and  Bidder  and 
Skrebitzry  claim  that  the  quantity  from  the  temporary  fistula  is 
2.5-5  grms.  per  kilo  in  the  same  time. 

In  regard  to  the  constitnents  and  comjjosition  of  the  pancreatic 
juice,  a  distinction  must  be  made  between  the  secretion  of  a  tem- 
porary and  of  a  permanent  fistula.  The  secretion  flowing  from  the 
former  is  in  dogs  a  clear,  colorless,  nearly-sirupy,  odorless  fluid  of 
an  alkaline  reaction  which  is  very  rich  in  albumin  and  sometimes 
containing  so  large  a  quatitity  that  it  coagulates  like  white  of  egg 
when  heated.  Besides  albumin  the  juice  contains  also  three  en- 
zymes— one  diastatic,  one  fat-spUiting,  and  one  which  dissolves 
profeids.  The  last-mentioned  has  been  called  tri/psi)i  by  Kuhne. 
Besides  the  above-mentioned  bodies  the  pancreatic  juice  habitually 
contains  small  quantities  of  leucin,  fat,  and  soaps.  As  mineral 
constituents  it  contains  chiefly  alkali  chlorides,  also  alkali  carbo- 
nates, and  some  phosphoric  acid,  lime,  magnesia,  and  iron. 

The  secretion  from  the  permanent  fistula  always  contains  less 
solids,  especially  albumin  and  enzymes,  than  that  from  a  tempo- 
rary fistula.  A  long  time  after  the  operation  it  is  more  fluid,  more 
strongly  alkaline,  and  the  property  which  the  juice  from  the  tem- 
porary flstula  has  of  dissolving  albumin  is  often  absent,  or  the 
secretion  shows  it  in  only  a  slight  degree.  As  an  example  of  the 
different  composition  of  the  juice  from  a  temporary  and  from  a 


202  PHYSIOLOGICAL  CEEMISTBT. 

permanent  fistula,  we  give  below  the  analyses  of  C.  Schmidt.    The 
figures  represent  parts  per  1000. 

Juice  from  a  Temporary  Juice  from  a  Permanent 

Fistula.  Fistula. 

a.  b.  a.  b.  c. 

Water 900.8  884.4  976.8  979.9  984.6 

Solids 99.2  115.6  23.3  20.1  15.4 

Organic  substance 90.4  16.4  12.4  9.2 

Ash 8.8  6.8  7,5  6.1 

The  mineral  constituents  of  the  secretion  from  the  temporary  fistula  con- 
sisted chiefly  of  NaCl,  7.4  p.  m. 

In  the  pancreatic  juice  of  rabbits  11-26  p.  m.  solids  have  been  found,  and 
in  that  from  sheep  14.3-36.9  p.  m.  In  the  pancreatic  juice  of  the  horse  9-17.5 
p.  m.  solids  have  been  found  ;  in  that  of  the  pigeon,  12-14  p.  m. 

The  human  pancreatic  juice  has  been  analyzed  by  Hekter  in  a  case  of 
stoppage  of  the  exit  of  the  juice  by  the  pressure  of  a  cancer.  This  juice, 
which  could  hardly  be  considered  as  normal,  was  clear,  alkaline,  without  odor, 
and  contained  the  three  enzymes.  It  contained  peptone,  but  no  other  pro- 
teid.  The  quantity  of  solids  was  24.1  p.  m.  Of  these  6.4  p.  m.  were  soluble 
in  alcohol.  It  contained  11.5  p.  m.  peptones  (and  enzymes)  and  6.2  p,  m. 
mineral  substances. 

Among  the  constituents  o.f  the  pancreatic  juice,  the  three 
enzymes  are  the  most  important. 

The  pancreatic  diastase,  which  according  to  Koeowik  and 
ZwEiFEL  is  not  found  in  new-born  infants  and  ■  does  not  appear , 
until  more  than  one  month  after  birth,  seems,  although  not  identi- 
cal with  ptyalin,  to  be  nearly  related  to  it.  The  pancreatic  diastase 
acts  very  energetically  upon  boiled  starch,  especially  at  -|-  37°  to 
40°  C,  and  besides  dextrin  yields  maltose  with  only  a  small  quantity 
of  glucose  (MuscuLUS  and  v.  MERiisrG). 

If  the  natural  pancreatic  Juice  is  not  to  be  obtained,  then  the 
gland,  best  after  it  has  been  exposed  a  certain  time  (24  hours)  in 
the  air,  may  be  treated  with  water  or  glycerin.  This_  infusion  or 
the  glycerin  extract  diluted  with  water  (when  a  glycerin  has  been 
used  which  has  no  reducing  action)  may  be  tested  directly  with 
starch-paste.  It  is  safer,  however,  to  first  precipitate_  the  enzyme 
from  the  glycerin  extract  by  alcohol,  and  wash  with  this  liquid,  dry 
the  precipitate  over  sulphuric  acid,  and  extract  with  water.  The 
enzyme  is  dissolved  by  the  water.  The  detection  of  sugar  may  be 
made  in  the  same  manner  as  in  the  saliva. 

The  fat-splitting  enzyme.  The  action  of  the  pancreatic  juice  on 
fats  is  twofold.  First,  the  neutral  fats  are  split  into  fatty  acids 
and  glycerin,  which  is  an  enzymotic  process;  and  secondly,  it  has 
also  the  property  of  emulsifying  the  fats. 


DIGESTION.  203 

The  action  of  the  pancreatic  juice  in  splitting  the  fats  may  be 
shown  in  the  following  way.  Shake  olive-oil  with  caustic  soda  and 
ether,  siphon  off  the  ether  and  filter  if  necessary,  then  shake  the 
ether  repeatedly  with  water  and  evaporate  at  a  gentle  heat.  In  this 
way  we  obtain  a  residue  of  fat  free  from  fatty  acids  which  is  com- 
pletely neutral,  and  which  dissolves  in  acid-free  alcohol  and  is  not 
colored  red  by  alkanet  tincture.  If  such  fat  is  mixed  with  quite  fresh 
alkaline  pancreatic  juice  or  with  a  freshly-prepared  infusion  of  the 
fresh  gland  and  treated  with  a  little  alkali  or  with  a  faintly  alkaline 
glycerm  extract  of  the  fresh  gland  (9  parts  glycerin  and  1  part  soda 
solution  of  Ifo  for  each  gramme  of  the  gland)  and  some  litmus 
tincture  added  and  the  mixture  warmed  to  -|-  37°  C,  the  alkaline 
reaction  will  gradually  disappear  and  an  acid  one  takes  its  place. 
This  acid  reaction  depends  upon  the  conversion  of  the  neutral  fats 
by  the  enzyme  into  glycerin  and  free  fatty  acids. 

The  splitting  of  the  neutral  fats  may  also  be  shown  more  exactly 
by  the  following  method.  The  mixture  of  neutral  fats  (absolutely 
free  from  fatty  acids)  and  pancreatic  juice  or  pancreas  infusion  is 
digested  at  the  temperature  of  the  body  and  treated  with  some 
soda  and  repeatedly  shaken  with  fresh  quantities  of  ether  until  all 
the  unsplit  neutral  fats  are  removed.  Then  it  is  made  acid  with 
sulphuric  acid,  after  which  shake  the  acid  liquid  with  ether,  evapo- 
rate the  ether,  and  test  the  residue  foi*  fatty  acids. 

Another  simple  process  for  the  demonstration  of  the  fat-splitting 
action  of  the  pancreas  glands  is  the  following  (Cl.  Bernard).  A 
small  portion  of  the  perfectly-fresh,  finely-divided  gland  substance 
is  first  soaked  in  alcohol  (of  90^).  Then  the  alcohol  is  removed  as 
far  as  possible  by  pressing  between  blotting-paper,  after  which  the 
pieces  of  gland  are  covered  with  an  ethereal  solution  of  neutral 
butter-fat  (which  may  be  obtained  by  shaking  milk  with  caustic 
soda  and  ether).  After  the  evaporation  of  the  ether  the  pieces  of 
gland  covered  with  butter-fat  are  pressed  between  two  watch-glasses 
and  then  gently  heated  to  37°  to  40°  C.  in  this  position.  After  a 
certain  time  a  marked  odor  of  butyric  acid  appears. 

The  action  of  the  pancreatic  juice  in  splitting  fats  is  a  process 
analogous  to  that  of  saponification,  the  neutral  fats  being  decom- 
posed, by  the  addition  of  the  elements  of  water,  into  fatty  acids  and 
glycerin  according  to  the  following  formula:  CaHj.Os.Rs  (neutral 
fat)  +  3H2O  =  C3H5.O3.H3  (glycerin)  +  3(H.0.R)  (fatty  acid). 
This  depends  upon  a  hydrolytic  splitting,  which  was  first  positively 
proved  by  Berkard  and  Berthelot.  The  pancreas  enzyme  also 
decomposes  other  esters  just  as  it  does  the  neutral  fats  (Nencki). 
The  pancreas-enzyme  which  decomposes  fats  has  been  less  studied 


204  PHYSIOLOGICAL  CHEMISTRY. 

than  the  other  pancreas-enzymes,  and  it  has  indeed  been  questioned 
whether  or  not  the  decomposition  of  the  neutral  fats  in  the  intestine 
may  not  be  effected  through  lower  organisms.  According  to  the 
investigations  of  Nen'Cki,  it  seems  that  the  pancreas  actually  con- 
tains an  enzyme  which  decomposes  fats.  This  enzyme,  which  is 
still  little  known,  appears  to  be  very  sensitive  to  acids,  and  it  is 
often  absent  in  acid  glands  not  perfectly  fresh.  If  a  watery  in- 
fusion of  the  gland  prepared  cold  be  treated  with  calcined  magnesia, 
then  the  enzyme  in  question  will,  according  to  Danilewski,  be 
retained  by  the  magnesia  precipitate. 

The  fatty  acids  which  are  split  off  by  the  action  of  the  pan- 
creatic juice  combine  in  the  intestine  with  the  alkalies,  forming 
soaps  which  have  a  strong  emulsifying  action  on  the  fats,  and 
thus  the  pancreatic  juice  becomes  of  great  importance  in  the  emul- 
sification  and  the  absorption  of  the  fats. 

Trypsin.  The  action  of  the  pancreatic  juice  in  digesting  pro- 
teids  was  first  observed  by  Beri^ ard,  but  first  proved  by  Corvisart. 
It  depends  upon  a  special  enzyme  called  by  Kuhne  trypsin. 
Strictly  speaking,  this  enzyme  does  not  occur  in  the  gland  itself. 
In  the  gland,  more  probably,  a  zymogen  occurs  from  which  the 
enzyme  is  split  off  or  formed  by  the  secretion,  also  by  the  action  of 
water,  acids,  alcohol,  and  other  substances.  According  to  Alber- 
TONi,  this  zymogen  is  found  in  the  gland  in  the  last  third  of  the 
intra-uterine  life. 

The  purest  trypsin  thus  far  prepared,  isolated  by  KiJHisrE,  is 
soluble  in  water  but  insoluble  in  alcohol  or  glycerin.  The  less  pure 
enzyme,  on  the  contrary,  is  soluble  in  glycerin.  If  the  solution  of 
the  enzyme  in  water  is  heated  to  the  boiling  point  with  the  addi- 
tion of  a  little  acid,  it  decomposes  into  coagulated  albumin  and 
peptone  (Kuhne).  It  is  destroyed  by  gastric  juice.  Like  other 
enzymes,  trypsin  is  characterized  by  its  physiological  action.  This 
action  consists  in  its  power  of  dissolving  albumin',  and  especially 
easily  fibrin,  in  alkaline,  neutral,  and  even  in  faintly  acid-reacting 
solutions. 

The  production  of  pure  trypsin  has  been  tried  by  various  ex- 
perimenters, Danilewski,  Hufner,  KtJHNE,  Loew,  and  others. 
The  purest  seems  to  have  been  prepared  according  to  the  rather  com- 
plicated method  of  KiJHNE.     In  studying  the  action  of  trypsin  a 


DIGESTION.  205 

Jess  pure  preparation  may  often  answer,  and  various  methods  of 
preparing  such  have  been  proposed,  but  we  cannot  describe  all  of 
them.  For  the  production  of  a  glycerin  extract  the  gland  should 
be  rubbed  with  glass  powder  or  pure  quartz-sand,  this  mass  care- 
fully mixed  with  acetic  acid  of  1%  (1  cc.  to  each  grm.  of  gland), 
then  for  each  part  of  the  gland-mass  add  10  parts  of  glycerin,  and 
filter  after  about  three  days.  By  precipitating  the  glycerin  extract 
with  alcohol  and  redissolving  the  precipitate  in  water,  we  obtain  a 
solution  which  has  a  powerful  digestive  action  (Heidenhain).  A 
watery  infusion  of  the  gland  may  be  made  only  after  it  has  been 
exposed  to  the  air  for  24  hours,  and  5-10  parts  of  water  for  each 
part  by  weight  of  the  gland  should  be  used.  The  simplest 
method  is  to  cut  the  gland  fine  and  place  it  in  a  flask  and  allow  it 
to  digest  with  water  to  which  5-10  cc.  of  chloroform  (Salkowski) 
or  ether  has  been  added  for  each  litre.  After  a  few  days  we 
obtain  in  this  way  a  powerful  infusion  which  keeps. 

The  action  of  trypsin  on  proteids  is  best  demonstrated  by  the 
use  of  fibrin.  Very  considerable  quantities  of  this  albuminous  body 
are  dissolved  by  a  small  amount  of  trypsin  at  37°-40°  0.  It  is  always 
necessary  to  make  a  control  test  with  fibrin  alone,  with  or  without 
the  addition  of  alkali.  Fibrin  is  dissolved  by  trypsin  without  any 
putrefaction ;  the  liquid  has  a  pleasant  odor  somewhat  like  bouillon. 
To  completely  exclude  putrefaction  a  little  thymol,  chloroform, 
or  ether  should  be  added  to  the  liquid.  Trypsin  digestion  differs 
essentially  from  pepsin  digestion  in  that  the  first  takes  place  in 
neutral  or  alkaline  reaction  and  not,  as  is  necessary  for  pepsin  di- 
gestion, in  an  acidity  of  1-2  p.  m.  HCl,  and  further  by  the  fact  that 
the  proteids  dissolve  in  the  trypsin  digestion  without  previous  ex- 
pansion. 

Many  circumstances  exert  a  marked  influence  on  the  rapidity 
of  the  trypsin  digestion.  With  an  increase  in  the  quantity  of 
enzyme  present  the  digestion  is  hastened  at  least  to  a  certain  point, 
and  the  same  is  also  true  of  an  increase  in  temperature  at  least  to 
about  +  40°  C,  at  which  temperature  the  albumin  is  very  rapidly 
dissolved  by  the  trypsin.  The  reaction  is  also  of  the  greatest  im- 
portance. Trypsin  acts  energetically  in  neutral,  or  still  better  in 
alkaline,  solutions,  and  best  in  an  alkalinity  of  3-4  p.  m.  NagCOs. 
Free  mineral  acids,  even  in  very  small  quantities,  completely  prevent 
the  digestion.  If  the  acid  is  not  actually  free,  but  combined  with 
albuminous  bodies,  then  the  digestion  may  take  place  quickly  when 


206  PHYSIOLOGICAL   CHEMISTRY. 

the  acid  combination  is  not  in  too  great  excess  (Chittenden  and 
Cummins).  Organic  acids  act  less  disturbingly,  and  in  tlie  presence 
of  0.3  p.  m.  lactic  acid  and  the  simultaneous  presence  of  proteid,  bile, 
and  common  salt  the  digestion  may  indeed  proceed  more  quickly 
than  in  a  faintly-alkaline  liquid  (Lindberger).  Foreign  bodie.^, 
such  as  borax  and  potassium  cyanide,  may  promote  digestion,  while 
bodies  such  as  mercuric,  fe^ic  and  other  salts  (Chittenden  and 
Cummins),  or  salicylic  acid  m  large  quantities  (Kuhne),  may  act 
preventively.  The  nature  of  the  proteids  is  also  of  importance. 
Unboiled  fibrin  is,  relatively  to  most  other  albuminous  bodies,  dis- 
solved so  very  quickly  that  the  digestion  test  with  raw  fibrin  gives 
an  incorrect  idea  of  the  power  of  trypsin  to  dissolve  coagulated 
albuminous  bodies  in  general.  An  accumulation  of  digestion,  pro- 
ducts tends  to  hinder  the  trypsin  digestion. 

The  Products  of  the  Trypsin  Digestion.  In  the  digestion  of  un- 
boiled fibrin  a  globulin  which  coagulates  at  +  55°-56°  C.  may  be 
obtained  as  an  intermediate  product  (Herrmann).  Moreover  from 
fibrin,  as  well  as  from  other  albuminous  bodies,  alhumoses  and 
peptones,  leucin,  tyrosin  and  aspartic  acid,  a  little  ammonia 
(Hirschler),  and  a  substance  whose  nature  is  not  known  and  which 
gives  a  beautiful  purple-red  liquid  with  chlorine  or  bromine  water 
in  acid  solution,  have  been  obtained.  When  putrefaction  has  not 
been  entirely  prevented  numerous  other  bodies  appear  which  will  be 
spoken  of  later  in  connection  with  the  putrefaction  process  going 
on  in  the  intestine.  In  the  trypsin  digestion,  in  contrast  to  the 
pepsin  digestion,  pure  peptones,  not  precipitated  by  ammonium  sul- 
phate, are  relatively  easily  and  quickly  formed.  The  peptone, 
according  to  KiJHNE  consists  entirely  of  antipeptone,  and  the  above- 
mentioned  decomposition  products,  leucin  and  the  others,  are  formed 
by  the  decomposition  of  the  hemipeptone.  We  will  now  consider 
leucin  and  tyrosin  decomposition  products  formed  by  the  trypsin 
digestion  of  proteids. 

Leucin,  CgHisNOg,  or  amido-caproic  acid,  C5Hio(NH2)COOH, 
besides  occurring  in  the  trypsin  digestion  of  proteids,  is  derived 
from  the  protein  substances  by  their  decomposition  on  boiling  with 
diluted  acids  or  alkalies,  by  melting  with  alkali  hydrates,  and  by 
putrefaction.  Because  of  the  ease  with  vrhich  leucin  and  tyrosin 
are  formed  in  the  decomposition  of  protein  substances,  it  is  diflficult 


DIGESTION.  207 

to  positively  decide  whether  these  bodies  when  found  in  the  tissues 
are  constituents  of  the  hving  body  or  are  only  to  be  considered  as 
decomposition  products  formed  after  death.  Leucin  has  been  found 
in  the  pancreas  and  its  secretion,  in  the  spleen,  thymus  and  lymph- 
glands,  in  the  thyroid  gland,  in  the  salivary  glands,  in  the  kidneys, 
brain,  and  liver  (but  mostly  in  disease).  It  also  occurs  in  the  wool 
of  sheep,  in  dirt  from  the  skin  (inactive  epidermis)  and  between 
the  toes,  and  its  decomposition  products  have  the  disagreeable  odor 
of  the  perspiration  of  the  feet.  It  is  found  pathologically  in 
atheromatous  ulcers,  ichthyosis  scales,  pus,  blood,  and  urine  (in  dis- 
eases of  the  liver).     Leucin  also  occurs  in  the  vegetable  kingdom. 

Leucin  may  be  prepared  synthetically  most  simply  by  the  action 
of  ammonia  on  monobrom-caproic  acid  (Hufnee).  On  heating 
with  fuming  hydriodic  acid  to  140°  C.  it  splits  into  ammonia  and 
caproic  acid.  On  heating  leucin  alone  it  decomposes  with  the  for- 
mation of  carbon  dioxide,  ammonia,  and  amylamin.  On  fusing 
with  caustic  alkali,  as  also  on  putrefaction,  it  yields  valerianic  acid 
and  ammonia. 

Leucin  crystallizes  when  pure  in  shining,  white,  very  thin 
plates,  usually  forming  round  knobs  or  balls,  either  appearing  like 
hyalin  or  alternating  light  or  dark  concentric  layers  which  consist 
of  radial  groups  of  crystals.  Leucin  as  obtained  from  the  animal 
fluids  and  tissues  is  very  easily  soluble  in  water  and  rather  easily  in 
alcohol.  Pure  leucin  is  soluble  with  difficulty;  it  dissolves  in  27 
parts  cold  water,  in  1040  parts  cold  and  in  800  parts  boiling  alco- 
hol. It  is  easily  dissolved  by  alkalies  and  acids.  On  slowly  heating 
to  170°  C.  it  melts  and  sublimes  in  white,  woolly  flakes  which  are 
similar  to  sublimed  zinc  oxide.  A  marked  odor  of  amylamin  is 
generated  at  the  same  time. 

The  solution  of  leucin  in  water  is  not,  as  a  rule,  precipitated  by 
metallic  salts.  The  boiling-hot  solution  may,  however,  be  precipi- 
tated by  a  boiling-hot  solution  of  copper  acetate.  If  the  solution 
of  leucin  is  boiled  with  sugar  of  lead  and  then  ammonia  be  added 
to  the  cooled  solution,  shining  crystalline  leaves  of  leucin-lead  oxide 
separate.  When  boiled  with  leucin,  copper  oxyhydrate  is  dissolved 
without  reduction. 

Leucin  is  recognized  by  the  appearance  of  the  balls  or  knobs 
under  the  microscope,  by  its  action  when  heated  (sublimation  test). 


208  PHYSIOLOOICAL   CHEMI8TBT. 

and  by  Scherer's  test.  This  last  consists  in  the  leucin  yielding  a 
colorless  residue  when  carefully  evaporated  with  nitric  acid  on 
platinum-foil,  and  this  residue  when  warmed  with  a  few  drops  of 
caustic  soda  gives  a  color  varying  from  a  pale  yellow  to  brown  (de- 
pending on  the  purity  of  the  leucin),  and  on  further  concentrating 
over  the  flame  it  agglomerates  into  an  oily  drop  which  rolls  about 
on  the  foil. 

Tyrosin,  CgHnNOg ,  or  p.  oxyphenyl-amidoproprionic  acid, 
H0.06H4.C2H3(]S[H2).COOH,  is  derived  from  most  protein  sub- 
stances (not  gelatin)  under  the  same  conditions  as  leucin,  which  it 
habitually  accompanies.  It  is  especially  found  with  leucin  in  large 
quantities  in  old  cheese  (Tvpos),  from  which  it  derives  its  name. 
Tyrosin  has  not  with  certainty  been  found  in  perfectly  fresh  organs, 
with  the  exception,  perhaps,  of  the  spleen  and  pancreas  of  cattle. 
It  occurs  in  the  intestine  in  the  digestion  of  albuminous  sub- 
stances, and  it  has  about  the  same  physiological  and  pathological 
importance  as  leucin. 

Tyrosin  was  prepared  by  Erlenmeyer  and  Lipp  from  p.  amido- 
phenylalanin  by  the  action  of  nitrous  acid.  On  fusing  with  caustic 
alkali  it  yields  p.  oxybenzoic  acid,  acetic  acid,  and  ammonia.  By 
putrefaction  it  may  yield  p.  hydrocoumaric  acid,  oxyphenyl-acetic 
acid,  and  p.  cresol. 

Tyrosin  in  a  very  impure  state  may  be  in  the  form  of  balls 
similar  to  leucin.  The  purified  tyrosin,  on  the  contrary,  appears  as 
colorless,  silky,  fine  needles  which  are  often  grouped  into  tufts  or 
balls.  It  is  soluble  with  difiiculty  in  water,  being  dissolved  by  2454 
parts  water  at  +  30°  C.  and  154  parts  boiling  water,  separating, 
however,  as  tufts  of  needles  on  cooling.  It  dissolves  more  easily 
in  the  presence  of  alkalies,  ammonia,  or  a  mineral  acid.  It  is 
difficultly  soluble  in  acetic  acid.  Crystals  of  tyrosin  separate  from 
an  ammoniacal  solution  on  the  spontaneous  evaporation  of  the 
ammonia.  It  is  not  soluble  in  alcohol  or  ether.  Tyrosin  is  known 
by  its  crystalline  form  and  by  the  following  reactions  : 

Piria's  Test.  Tyrosin  is  dissolved  in  concentrated  sulphuric 
acid  by  the  aid  of  heat,  by  which  tyrosin  sulphuric  acid  is  formed; 
it  is  allowed  to  cool,  diluted  with  water,  neutralized  by  BaCOs, 
and  filtered.  On  the  addition  of  a  solution  of  ferric  chloride,  the 
filtrate  gives  a  beautiful  violet  color.     This  reaction  is  impeded  by 


DIGESTION.  209 

the  presence  of  free  mineral  acids  and  by  the  addition  of  too  much 
ferric  chloride. 

Hofmann's  Test.  If  some  water  is  poured  on  a  small  quantity 
of  tyrosin  in  a  test-tube  and  a  few  drops  of  Millon's  reagent 
added  and  then  the  mixture  boiled  for  a  certain  time,  the  liquid 
becomes  a  beautiful  red  and  then  yields  a  red  precipitate.  Or 
mercuric  nitrate  may  first  be  added,  then,  after  this  has  boiled, 
nitric  acid  which  contains  some  nitrous  acid. 

Scherbr's  Test.  If  tyrosin  is  carefully  evaporated  to  dryness 
with  nitric  acid  on  platinum-foil,  a  beautiful  yellow  residue  (uitro- 
tyrosin  nitrate)  is  obtained,  which  gives  a  deep  reddish-yellow  color 
with  caustic  soda.  This  test  is  not  characteristic,  as  other  bodies 
give  a  similar  reaction. 

Leucin  and  tyrosin  may  be  prepared  in  large  quantities  by 
boiling  albuminous  bodies  or  albuminoids  with  dilute  mineral 
acids.  Ordinarily  we  boil  hoof-shavings  (2  parts)  with  dilute  sul- 
phuric acid  (5  parts  concentrated  acid  and  13  parts  water)  for  24 
hours.  After  boiling  the  solution  it  is  diluted  with  water  and  neu- 
tralized while  still  warm  with  milk  of  lime  and  then  filtered.  The 
calcium  sulphate  is  repeatedly  boiled  with  water,  and  the  several 
filtrates  are  united  and  concentrated.  The  lime  is  precipitated 
from  the  concentrated  liquid  by  oxalic  acid  and  the  precipitate 
filtered  off,  repeatedly  boiled  with  water,  all  filtrates  united  and 
evaporated  to  crystallization.  What  first  crystallizes  consists 
chiefly  of  tyrosin  with  only  a  little  leucin.  By  concentrution  a  new 
crystallization  may  be  produced  in  the  mother-liquor,  which  consists 
of  leucin  with  some  tyrosin.  To  separate  leucin  and  tyrosin  from 
each  other  their  different  solubilities  in  water  may  be  taken  advan- 
tage of  in  preparing  them  on  a  large  scale,  but  surer  and  better 
results  are  obtained  by  the  following  method  of  Hlasiwetz  and 
Habermann.  The  crystalline  mass  is  boiled  with  a  large  quantity 
of  water  and  enough  ammonia  to  dissolve  it.  To  this  boiling-hot 
solution  enough  basic  lead  acetate  is  added  until  the  precipitate 
formed  is  nearly  white;  now  filter,  heat  the  light  yellow  filtrate  to 
boiling,  neutralize  with  sulphuric  acid,  and  filter  while  boiling  hot. 
After  cooling,  nearly  all  the  tyrosin  is  precipitated,  while  the  leucin 
remains  in  the  solution.  The  tyrosin  may  be  purified  by  recrys- 
tallizing  from  boiling  water  or  from  ammoniacal  water.  The 
above-mentioned  mother-liquor  rich  in  leucin  is  treated  with  HgS, 
the  filtrate  concentrated  and  boiled  with  an  excess  of  freshly-pre- 
cipitated copper  oxyhydrate.  A  part  of  the  leucin  is  precipitated, 
and  the  residue  remains  in  the  solution  and  partly  ci-ystallizes  as  a 
cuprous  compound  on  cooling.     The  copper  is  removed  from  the 


210  PHYSIOLOGICAL   CHEMISTRY. 

precipitate  and  solution  by  means  of  HgS,  the  filtrate  decolorized 
when  necessary  with  animal  charcoal,  strongly  concentrated  and 
allowed  to  crystallize.  The  leucin  obtained  from  the  precipitate  is 
quite  pure,  while  that  from  the  solution  is  somewhat  contaminated. 

If  one  is  working  with  small  quantities,  the  crystals,  which 
consist  of  a  mixture  of  the  two  bodies,  may  be  dissolved  in  water 
and  this  solution  precipitated  with  basic  lead  acetate.  The  filtrate 
is  treated  with  HgS,  the  new  filtrate  evaporated  to  dryness,  and  the 
residue  treated  with  warm  alcohol  which  dissolves  the  leucin  but 
not  the  tyrosin.  The  remaining  tyrosin  is  purified  by  recrystalliza- 
tion  from  ammoniacal  alcohol.  Leucin  may  be  purified  by  recrys- 
tallization  from  boiling  alcohol  or  by  precipitating  it  as  leucin  lead 
oxide,  treating  the  precipitate  suspended  in  water  with  HgS  and 
evaporating  the  filtered  solution  to  crystallization. 

To  detect  the  presence  of  leucin  and  tyrosin  in  animal  fluids  or 
tissues  the  albumin  must  first  be  removed  by  coagulation  with  the 
addition  of  acetic  acid  and  then  jarecipitated  by  basic  lead  acetate. 
The  filtrate  is  treated  with  HaS,  this  filtrate  evaporated  to  a  syrup 
or  to  dryness,  and  the  two  bodies  in  the  residue  are  separated  from 
each  other  by  boiling  alcohol  and  then  purified  as  above  stated. 

Aspartic  Acid,  C4H7NO4,  or  amido-succinic  acid,  C2H3(]S[H2). 
(C00H)2.  This  acid  has  been  obtained  in  the  trypsin  digestion  of 
fibrin  (Eadziejewski  and  Salkowski)  and  of  glutin  (v.  KisriE- 
eiem).  It  may  also  be  obtained  by  the  decomposition  of  albumin- 
ous bodies  or  albuminoids  with  acids  (see  Chap.  II).  It  has  also 
been  found  in  beet-root  molasses,  and  lastly  it  is  very  widely  dif- 
fused in  the  vegetable  kingdom  as  the  amid  asparagine  (amido- 
succinic-acid  amid),  which  seems  to  be  of  the  greatest  importance 
in  the  development  and  formation  of  the  albuminous  bodies. 

Aspartic  acid  dissolves  in  boiling  water  and  crystallizes  on  cool- 
ing into  rhombic  prisms.  It  is  optically  active,  and  is  dextrogyrate 
in  a  solution  strongly  acid  with  nitric  acid.  It  forms  with  copper 
oxide  a  crystalline  combination  which  is  soluble  in  boiling-hot 
water  and  nearly  insoluble  in  cold  water,  and  which  may  be  used  in 
the  preparation  of  the  pure  acid  from  a  mixture  with  other  bodies. 

The  action  of  trypsin  on  other'  bodies  has  not  been  thoroughly 
studied.  An  enzyme  has  been  found  in  the  pancreas-gland  of  the 
pig  and  certain  herbivora  which  causes  a  coagulation  of  neutral  or 
alkaline  milk  (Kuhne  and  Roberts).  Gelatin  is  dissolved  by  the 
pancreatic  juice  and  is  converted  into  gelatin  peptone.  In  tests 
with  a  very  impure  infusion  (self- digestion  of  the  gland  in  the  pres- 


DIGESTION.  211 

ence  of  gelatine),  besides  gelatin  peptone  Nencki  obtained  leucin, 
glycocoll,  ammonia,  a  base,  CgHuN,  and  other  products.  The  pure 
enzyme,  according  to  Kuhne,  gives  neither  glycocoll  nor  leucin 
with  gelatin.  The  gelatin-giving  substance  of  the  connective  tis- 
sues is  not  directly  dissolved  by  trypsin,  but  only  after  it  has  been 
treated  with  acid  or  after  soaking  in  water  at  -f-  70°  C.  By  the 
action  of  trypsin  on  hyalin  cartilage  the  cells  dissolve,  leaving  the 
nucleus.  The  basis  is  softened  and  shows  an  indistinctly-con- 
structed network  of  collagenous  substance  (Kuhjste  and  Ewald). 
The  elastic  substance,  the  stricctureless  membrane,  and  the  mem- 
brane  of  the  fat-cells  are  also  dissolved.  Parenchymatous  organs, 
such  as  the  liver  and  the  muscles,  are  dissolved  to  the  nucleus,  and 
also  connective  tissue,  fat-corpuscles,  and  the  remainder  of  the 
nervous  tissue.  If  the  muscles  are  boiled,  then  the  connective  tissue 
is  also  dissolved.  Trypsin  seems  to  be  without  action  on  chitin 
and  horny  substance.  Oxyhmnoglobin  is  decomposed  by  trypsin 
with  the  splitting  off  of  hsematin.  Hcemoglobin,  on  the  contrary, 
when  the  access  of  oxygen  is  completely  prevented,  is  not  decom- 
posed by  trypsin  (Hoppe-Seylee).  Trypsin  does  not  act  on  fats 
or  carbohydrates. 

It  was  already  brought  out  above  that  trypsin  does  not  exist 
ready  formed  in  the  gland,  but  more  likely,  as  Heidenhain  has 
shownj  the  gland  contains  a  corresponding  zymogen.  The  maxi- 
mum quantity  of  such  zymogen  in  the  gland  occurs  14-16-18  hours 
after  an  abundant  meal,  and  the  minimum  6-10  hours  after. 
This  zymogen  is  not  changed  by  glycerin  so  that  it  forms  trypsin, 
but  is  easily  changed  by  water  and  acids.  A  soda  solution  of  1-1.5^, 
on  the  contrary,  prevents  almost  entirely  the  changing  of  the 
zymogen.  If  we  allow  the  gland  to  lie  in  the  air  it  gradually 
becomes  acid,  and  this  leads  to  the  formation  of  an  enzyme  in  which 
the  oxygen  seems  to  be  active,  as  is  usual  in  the  conversion  of  the 
zymogen  into  trypsin.  It  is  very  probable  also  that  the  two  other 
enzymes  are  formed  from  con-esponding  zymogens,  and  this  has 
been  shown  to  be  plausible  in  regard  to  the  diastatic  enzymes  by 

LiVEESIDGE. 

After  a  plentiful  meal  Heidenhain  found  in  dogs  in  the  first 
stages  of  digestion,  when  the  secretion  of  pancreatic  juice  was 
most  active,  that  the  glandular  cells  became  smaller  owing  to  the 


212  PHYSIOLOGICAL   CHEMISTRY. 

consumption  of  the  inner  granular  zone,  while  the  outer  zone  at  the 
same  time  took  up  new  material  and  became  larger.  In  these  stages 
the  quantity  of  zymogen  is  smallest.  At  a  later  period,  12-20  hours 
after  a  meal,  the  inner  zone  is  re-formed  from  the  outer,  and  the 
larger  this  zone  is  the  larger  the  quantity  of  zymogen  in  the  gland 
seems  to  be.  The  zymogen  consequently  belongs  to  the  inner  zone, 
and  the  secretion  consists  therefore,  at  least  in  part,  in  a  destruc- 
tion or  dissolution  of  this  zone  whereby  the  substance  of  the  gland 
itself  is  changed  into  the  secretion  (Heidenhain).  This  view, 
however,  is  in  opposition  to  that  of  Lewaschew,  who  observed 
that  in  animals  which  have  starved  and  whose  pancreas-glands  are 
nearly  free  from  zymogen,  the  inner  granular  zone  is  just  as  much 
developed  as  under  normal  conditions  and  contains  abundant  quan- 
tities of  zymogen.  We  are  still  completely  in  the  dark  regarding 
the  nature  of  the  chemical  processes  which  take  place  in  the  con- 
version of  the  zymogen  into  the  enzyme. 


V.    The  Chemical  Processes  in  the  Intestine. 

The  action  which  belongs  to  each  digestive  secretion  may  be 
essentially  changed  by  mixing  with  other  digestive  fluids;  and  since 
the  digestive  fluids  which  flow  into  the  intestine  are  mixed  with 
still  another  fluid,  the  bile,  it  will  be  readily  understood  that  the 
combined  action  of  all  these  fluids  in  the  intestine  makes  the 
chemical  processes  going  on  therein  very  complicated. 

As  the  acid  of  the  gastric  juice  acts  destructively  on  ptyalin,  this 
enzyme  has  no  further  diastatic  action,  even  after  the  acid  of  the 
gastric  juice  has  been  neutralized  in  the  intestine.  The  bile  has,  at 
least  in  certain  animals,  a  faint  diastatic  action  which  in  itself  can 
hardly  be  of  any  great  importance,  but  which  shows  that  the  bile 
has  not  a  preventive  but  rather  a  beneficial  influence  on  the 
energetic  diastatic  action  of  the  pancreatic  juice  and  the  faint 
diastatic  action  of  the  intestinal  juices.  Martin  and  Williams 
observed,  in  experiments  made  recently,  a  beneficial  action  of  the 
bile  on  the  diastatic  action  of  the  pancreas  infusion.  To  this  may 
be  added  that  the  organized  ferments  which  occur  habitually  in 
the  intestine   and  sometimes  in  the  food  have  partly  a  diastatic 


DIGESTION.  213 

action  and  partly  produce  a  lactic-acid  and  butyric-acid  fermen- 
tation. 

The  maltose  which  is  formed  from  the  starch  seems  to  be  con- 
verted into  glucose  in  the  intestine.  The  cellulose,  especially  the 
finer  and  more  tender,  is  undoubtedly  partly  dissolved  in  the  intes- 
tine ;  the  products  formed  hereby  are  not  very  well  known.  It  has 
been  shown  by  Tappenier  that  cellulose  may  produce  a  marsh-gas 
fermentation  in  the  intestines  caused  by  the  action  of  a  micro- 
organism; but  we  do  not  know  to  what  extent  the  cellulose  is  de- 
stroyed and  what  part  is  valueless  for  the  organism. 

Bile  possesses  the  power  of  dissolving  fats  in  so  slight  a  degree 
that  it  is  scarcely  worthy  of  mention.  It  is,  however,  without  doubt 
of  greater  importance  that  the  bile,  asNENCKi  has  shown,  facilitates 
the  fat-splitting  action  of  the  pancreatic  juice.  This  splitting  of 
the  fats  into  fatty  acids  and  glycerin  is  an  important  factor  in  the 
absorption  of  the  fats.  The  fatty  acids  combine  with  tlie  alkalies 
of  the  bile  and  most  readily  with  the  alkalies  of  the  intestinal  and 
pancreatic  juices,  producing  soaps  which  may  be  partly  absorbed 
as  such  and  partly  exercise  a  powerful  action  on  the  absorption  of 
the  fats.  There  is-  no  doubt  that  the  chief  part  of  the  fats  in  the 
foods  is  absorbed  as  a  fine  emulsion,  and  for  this  reason  the  soaps 
are  of  such  importance  in  the  formation  of  this  emulsion. 

If  to  a  soda  solution  of  about  2  p.  m.  Na2C03  we  add  pure, 
actually  neutral  olive-oil  in  not  too  large  quantity,  we  obtain,  after 
vigorous  shaking,  a  transient  emulsion.  If,  on  the  contrary,  we 
add  to  the  same  quantity  of  soda  solution  an  equal  amount  of  com- 
mercial olive-oil  (which  always  contains  free  fatty  acids),  we  need 
only  turn  the  vessel  over  for  the  two  liquids  to  mix  and  immediately 
we  have  a  very  finely-divided  and  permanent  emulsion  making  the 
liquid  appear  like  milk.  The  free  fatty  acids  of  the  always  some- 
what rancid  commercial  oil  combine  with  the  alkali  forming  soaps, 
which  act  to  emulsify  the  fats  (BRticKE,  Gad).  This  emulsifying 
action  of  the  fatty  acids  split  off  by  the  pancreatic  juice  is  undoubt 
edly  assisted  by  the  habitual  occurrence  of  free  fatty  acids  in  the 
food,  and  also  by  the  splitting  off  of  fatty  acids  from  the  neutral 
fats  by  the  putrefaction  in  the  intestine.  These  fatty  acids  must 
also  combine  with  the  alkalies  in  the  intestine  and  form  soaps. 

This  emulsification  of  fats  by  means  of  the  action  of  the  pan- 


214  PHYSIOLOGICAL   CEEMISTBY. 

creatic  juice  or  by  soaps  formed  in  other  ways  can  only  take  place 
in  an  alkaline  solution.  In  the  contents  of  the  intestine,  as  long^ 
as  they  are  acid,  such  an  emulsion  can  hardly  occur.  On  the  con- 
trary, it  undoubtedly  occurs  at  the  point  where  the  fat  comes  in 
contact  with  an  alkaline  secretion  under  a  mucous  membrane,  or 
in  general  where  it  meets  with  sufficient  alkali  to  form  an  emul- 
sion. In  the  acid  contents  of  the  intestines  of  dogs,  which  had 
been  kept  on  food  rich  in  fat,  LuDwiG  and  Cash  observed  no 
emulsion.  After  tying  the  two  pancreas  excretory  ducts  they 
found  a  remarkably  fine  emulsion  in  the  chylous  vessels,  though 
the  fat  in  the  contents  of  the  intestine  was  not  emulsified.  In 
this  case  it  is  possible  that  the  free  fatty  acid  which  is  hardly  ever 
absent  in  the  fat  of  the  food,  and  which  may  be  produced  also  by 
putrefaction  in  the  intestine,  forms  soaps  with  the  alkali  of  the 
mucous  coat  of  the  intestine  and  produces  the  emulsion  in  the 
chylous  vessels. 

Claude  Bernard  found  long  ago  in  his  experiments  on  rab- 
'bits,  in  which  animals  the  choledochus  duct  to  the  small  intestine 
was  inosculated  above  the  pancreas  passages,  that  when  their  food 
contained  a  large  proportion  of  fat  the  chylous  vessels  of  the  intes- 
tine above  the  pancreas  passages  were  transparent,  but  below  the 
same  they  were  milky-white,  and  from  this  concluded  that  the  bile 
alone,  without  the  pancreatic  juice,  does  not  emulsify  fats.  Dastre 
tried  the  reverse  experiment  in  dogs,  namely,  tying  the  choledo- 
chus duct  and  producing  a  biliary  fistula,  through  which  the  bile 
would  flow  into  the  intestine  below  the  mouth  of  the  pancreatic 
passages.  When  the  animals  were  killed  after  a  meal  rich  in  fat, 
the  chylous  vessels  were  first  milky-white  below  the  opening  of  the 
biliary  fistula.  Dastre  draws  the  following  conclusion  from  this  : 
that  combined  action  of  the  bile  and  the  pancreatic  juice  is  neces- 
sary for  the  absorption  of  the  fats — a  deduction  which  coincides 
with  the  above-mentioned  observations  of  Nencki. 

Bile  has  no  solvent  action  on  proteids,  but  still  it  may  have  an 
influence  on  their  digestion.  The  acid  contents  of  the  stomach, 
containing  an  abundance  of  proteids,  give  with  the  bile  a  precipi- 
tate of  proteids  and  bile-acids.  This  precipitate  carries  a  part  of 
the  pepsin  with  it,  and  for  this  reason  and  on  account  of  the  partial 
or  complete  neutralization  of  the  acid  of  the  gastric  juice  by  the 
alkali  of  the  bile  and  the  pancreatic  juice  the  pepsin  digestion  can- 


DIGESTION.  215 

not  proceed  further  m  the  intestine.  On  the  contrary,  the  bile 
does  not  disturb  the  digestion  of  albumin  by  means  of  the  pancre- 
atic juice  in  the  intestine.  The  action  of  these  digestive  secre- 
tions, as  above  stated,  is  not  disturbed  by  the  bile,  especially  not  by 
the  faintly-acid  reaction  due  to  organic  acids  which  are  habitually 
found  in  the  upper  parts  of  the  intestine.  In  a  dog  killed  while 
digestion  is  going  on,  the  faintly-acid,  bile-containing  matter  of  the 
intestine  shows  a  strong  digestive  action  on  albumin. 

The  precipitate  formed  on  the  mixing  of  the  acid  contents  of 
the  stomach  and  the  bile  dissolves  easily — partly  by  the  acid  reac- 
tion— in  an  excess  of  the  bile,  also  in  the  NaCl  produced  by  the 
neutralization  of  the  hydrochloric  acid  of  the  gastric  juice.  Since 
in  man  the  exit  passages  of  the  bile  and  the  pancreatic  juice  open 
near  one  another,  and  therefore  the  acid  contents  of  the  stomach 
are  probably  immediately  neutralized  by  the  bile  as  soon  as  it 
enters,  it  is  doubtful  whether  a  precipitation  of  albumin  by  the  bile 
occurs  in  the  intestine. 

Besides  the  previously-mentioned  processes  caused  by  enzymes, 
tliere  are  others  of  a  different  nature  going  on  in  the  intestine, 
namely,  the  putrefaction  processes  caused  by  micro-organisms. 
These  are  less  intense  in  the  upper  parts  of  the  intestine,  but 
increase  in  intensity  towards  the  lower  part  of  the  same,  and 
decrease  in  the  laTge  intestine  because  of  the  absorption  of  water. 
A  positive  proof  that  the  micro-organisms  are  active  in  these 
processes  lies  in  the  fact  that  they  occur  very  abundantly  in  the 
contents  of  the  intestine ;  and  it  is  to  be  remarked  that  these 
organisms  occur  in  largest  quantities  in  the  lower  parts  of  the 
intestine,  where  the  contents  have  the  most  disagreeable  odor. 
No  putrefaction  occurs,  on  the  contrary,  in  the  intestinal  canal  of 
the  foetus,  which  follows  from  the  fact,  proved  by  Zweifel, 
Hoppe-Seyler,  and  Senator,  that  in  the  contents  of  the  same 
only  undecomposed  bile-acids  and  bile-pigments  occur,  while  the 
otherwise  regularly-occurring  products  of  putrefaction  in  the 
intestinal  canal  are  absent. 

The  putrefaction  processes  in  tlie  intestine  are  somewhat  differ- 
ent from  those  of  the  pancreas  digestion ;  and  these  two  processes 
are  essentially  different  from  each  other  in  the  products  which  they 
yield.  In  the  pancreatic  digestion  there  are  formed,  so  far  as  is 
known,  besides  albumoses  and  peptones,  amido-acids  and  ammonia. 


216  PHYSIOLOGICAL   CHEMISTRY. 

In  the  putrefaction  of  the  proteids  we  have,  indeed,  the  same  pro- 
ducts formed  at  the  beginning,  but  the  decomposition  proceeds 
considerably  further  and  a  number  of  products  are  developed, 
which  have  become  known  through  the  labors  of  numerous  inves- 
tigators, Nencki,  Baumajstn,  Briegek,  H.  and  E.  Salkowski. 
The  products  which  are  formed  in  the  putrefaction  of  proteids  are 
(in  addition  to  alhumoses,  pejjtones,  amido-acids,  and  ammonia) 
indol,  shatol,  paracresol,  phenol,  flienyl-^pro'pionic  acid,  oxi^pTienyl- 
acetic  acid,  also  paraoxyplienyl-acetic  acid  and  Tiydroparacoumaric 
acid  (besides  paracresol,  produced  in  the  putrefaction  of  tyrosin), 
volatile  fatty  acids,  carbon  dioxide,  hydrogen,  marsh-gas,  and  sul- 
phuretted hydrogen.  In  the  putrefaction  of  gelatin  neither  tyrosin 
nor  indol  is  formed,  while  glycocoll  is  produced. 

Among  these  products  of  decomposition  a  few  are  of  special 
interest  because  of  their  behavior  within  the  organism,  and  because 
after  their  absorption  they  pass  into  the  urine.  A  few,  such  as  the 
oxyacids,  pass  unchanged  into  the  urine,  while  others,  such  as 
phenol,  are  transformed  into  ethereal  sulphuric  acids  by  synthesis, 
and  are  eliminated  by  the  urine  ;  others,  on  the  contrary,  such  as 
indol  and  skatol,  are  only  converted  into  ethereal  sulphuric  acids 
after  oxidation  (for  details  see  Chapter  XIV).  The  quantity  of 
these  bodies  in  the  urine  varies  also  with  the  extent  of  the  putre- 
faction processes  in  the  intestine  ;  at  least  this  is  true  for  the  ethe- 
real sulphuric  acids.  Their  quantity  increases  with  a  stronger  pu- 
trefaction, and  the  reverse  takes  place,  as  Baumajstf  has  shown  by 
experiments  on  dogs,  when  the  intestine  has  been  disinfected  by 
calomel,  as  then  they  disappear  from  the  urine. 

Among  the  products  of  putrefaction  developed  in  the  intestine, 
indol  and  skatol  must  be  carefully  discussed. 

CH 

Indol,     OgHjN  =  CgHi  CH,    and    Skatol,    or    methyl- 

\      / 
NH 

C.C.Hs 
INDOL,  CgHglSr  =  CeH^  OH,  are  two  bodies  which  stand 


NH 


DIGESTION.  217 

in  close  relationship  to  the  indigo  substances,  and  which  are 
formed  from  the  albuminous  bodies  by  their  putrefaction,  or  by 
^  fusion  with  caustic  alkali.  Hence  they  occur  habitually  in  the 
human  intestinal  canal  and  after  oxidation  into  indoxyl  and 
skatoxyl  respectively,  pass,  at  least  partly,  into  the  urine  as  the 
corresponding  ethereal  sulphuric  acids,  but  also  as  glycuronic 
acids. 

These  two  bodies  have  been  prepared  synthetically  in  many 
ways.  Both  may  be  obtained  from  indigo  by  reducing  it  with  tin 
and  hydrochloric  acid  and  heating  this  reduction  product  with 
zinc-dust  (Baeyee).  Indol  may  be  formed  from  skatol  by  passing 
it  through  a  red-hot  tube.  Indol  suspended  in  water  is  in  part 
oxidized  into  indigo-blue  by  ozone  (Nencki). 

Indol  and  skatol  crystallize  in  shining  leaves,  and  their  melting 
points  are  +  52°  and  95°  respectively.  Indol  has  a  peculiar  excre- 
mentitious  odor,  while  skatol  has  an  intense  fetid  odor  (skatol  ob- 
tained from  indigo  should  be  odorless).  Both  bodies  are  easily 
volatilized  by  steam,  skatol  more  easily  than  indol.  They  may  both 
be  removed  from  the  watery  distillate  by  ether.  Skatol  is  the  more 
insoluble  of  the  two  in  boiling  water.  Both  are  easily  soluble  in 
alcohol,  and  give  with  picric  acid  a  combination  consisting  of  red 
crystalline  needles.  If  a  mixture  of  the  two  picrates  be  distilled 
with  ammonia,  they  both  pass  over  without  decomposition  ;  but  if 
they  are  distilled  with  caustic  soda,  the  indol  is  decomposed  but 
not  the  skatol.  The  watery  solution  of  indol  gives  with  fuming 
nitric  acid  a  red  liquid,  and  then  a  red  precipitate  of  nitroso-indol 
nitrate  (Baeyee).  It  is  better  to  first  add  two  or  three  drops  of 
nitric  acid,  and  then  a  2%  solution  of  potassium  nitrite,'  drop  by 
drop  (Salkowski).  Skatol  does  not  give  this  reaction.  An 
alcoholic  solution  of  indol  treated  with  hydrochloric  acid  colors  a 
pine  chip  cherry-red.  Skatol  does  not  give  this  reaction.  Skatol 
dissolves  in  concentrated  hydrochloric  acid  with  a  violet  coloration. 

For  the  detection  of  indol  and  skatol  in,  and  their  preparation 
from,  excrement  and  putrefying  masses,  the  main  points  of  the 
usual  method  are  as  follows:  The  mass  is  distilled  after  acidifying 
with  acetic  acid;  the  distillate  is  then  treated  with  alkali  (to  com- 
bine with  any  phenol  which  may  be  present  at  the  same  time)  and 
again  distilled.     From  this  second  distillate  the  two  bodies,  after 


218  PHYSIOLOGICAL  CEEMI82BT. 

the  addition  of  hy  droll  chloric  acid,  are  precipitated  by  picric  acid. 
The  picrate  precipitate  is  then  distilled  with  ammonia.  The  two 
bodies  are  obtained  from  the  distillate  by  repeated  shaking  with 
ether  and  evaporation  of  the  several  ethereal  extracts.  The  residue, 
containing  indol  and  skatol,  is  dissolved  in  a  very  small  quantity  of 
absolute  alcohol  and  treated  with  8-10  vols,  of  water.  Skatol  is 
precipitated,  but  not  the  indol.  The  further  treatment  necessary 
for  their  separation  and  purification  will  be  found  in  other  works. 

The  gases  which  are  produced  by  the  putrefactive  processes  are 
mixed  in  the  intestinal  tract  with  the  atmospheric  air  swallowed 
with  the  saliva,  and  as  the  gas  generated  by  different  foods  vary, 
so  the  mixture  of  gases  after  various  foods  should  have  a  dissimilar 
composition.  This  is  found  to  be  true.  Oxygen  is  only  found  in 
very  faint  traces  in  the  intestine;  this  may  be  accounted  for  in 
part  by  the  formation  of  reducing  substances  in  the  fermentation 
processes  which  combine  with  the  oxygen,  and  partly,  perhaps 
chiefly,  to  a  diffusion  of  the  oxygen  through  the  tissues  of  the  walls 
of  the  intestine.  To  show  that  these  processes  take  place  mainly 
in  the  stomach  the  reader  is  referred  to  page  189,  on  the  composi-, 
tion  of  the  gases  of  the  stomach.  Nitrogen  is  habitually  found  in 
the  intestine,  and  it  is  probably  due  chiefly  to  the  swallowed  air, 
or  perhaps  in  part,  as  Bunge  claims,  to  a  diffusion  of  nitrogen 
from  the  tissues  of  the  intestinal  walls  to  the  intestine.  The 
^carbon  dioxide  originates  partly  from  the  putrefaction  of  the  pro- 
teids,  partly  from  the  lactic-acid  and  butyric-acid  fermentation  of 
carbohydrates,  and  partly  from  the  setting  free  of  carbon  dioxide 
from  the  alkali  carbonates  of  the  pancreatic  and  intestinal  juices 
by  their  neutralization  by  the  hydrochloric  acid  of  the  gastric  juice 
and  by  organic  acids  formed  in  the  fermentation.  Hydrogen  occurs 
in  largest  quantities  after  a  milk  diet  and  in  smallest  quantities 
after  a  purely  meat  diet.  This  gas  seems  to  be  formed  chiefly  from 
the  butyric-acid  fermentation  of  carbohydrates,  although  it  may 
occur  in  large  quantities  in  the  putrefaction  of  proteids  under  cer- 
tain circumstances.  There  is  no  doubt  that  the  sulflnireUed 
hydrogen  which  occurs  normally  in  the  intestine  originates  from 
the  proteids.  The  marsh-gas  undoubtedly  originates  in  the  putre- 
faction of  proteids.  As  proof  of  this  Euge  found  26A5fo  marsh- 
gas  in  the  human  intestine  after  a  meat  diet.     He  found  a  still 


DIGESTION.  219 

greater  quantity  of  this  gas  after  a  diet  consisting  of  leguminous 
plants;  this  coinsides  with  the  observation  that  marsh-gas  may  be 
produced  by  a  fermentation  of  carbohydrates,  but  especially  of  cel- 
lulose (Hoppe-Seylek,  Tappeniee).  Such  an  origin  of  marsh- 
gas,  especially  in  herbivora,  is  to  be  expected.  A  small  part  of  the 
mai-sh-gas  and  carbon  dioxide  may  also  depend  on  the  decomposition 
of  lecithin  (Hasebroek). 

Putrefaction  in  the  intestine  not  only  depends  upon  the  com- 
position of  the  food,  but  also  upon  the  albuminous  secretions  aiid 
the  bile.  Among  the  constituents  of  bile  which  are  changed  or 
decomposed,  we  have  not  only  the  pigments — produced  from  the 
bilirubin,  as  is  generally  assumed,  hydrobilirubin  and  brown  pig- 
ments— but  also  the  bile-acids,  especially  taurocholic  acid.  Glyco- 
ciiolic  acid  is  more  stable  and  a  part  is  found  unchanged  in  the  ex- 
crement of  certain  animals,  while  taurocholic  acid  is  so  completely 
decomposed  that  it  is  entirely  absent  in  the  faeces.  In  the  foetus, 
in  Avhose  intestinal  tract  no  putrefaction  processes  occur,  we  find, 
on  the  contrary,  undecomposed  bile-acids  and  bile-j^igments  in  the 
contents  of  the  intestine.  That  the  secretion  rich  in  albumin  is 
an  important  element  in  putrefaction  in  the  intestine  follows  from 
the  fact  that  putrefaction  may  also  continue  during  fasting.  From 
the  observations  of  Muller  on  Cetti  it  was  found  that  the  elimi- 
nation of  indican  during  hunger  rapidly  decreased  and  after  the 
third  day  of  starvation  it  had  entirely  disappeared,  while  the  phenol 
elimination,  which  at  first  decreased  so  that  it  was  nearly  minimum, 
increased  again  from  the  fifth  day  of  starvation  and  on  the  eighth 
or  ninth  day  it  was  three  to  seven  tmies  as  much  as  in  man 
under  ordinary  circumstances.  In  dogs,  on  the  contrary,  the  elimi- 
nation of  indican  during  starvation  is  considerable,  but  the  phenol 
elimination  is  minimum.  Among  the  secretions  which  undergo 
putrefaction  in  the  intestine,  the  pancreatic  juice,  which  putrifies 
most  readily,  takes  first  place,  Pisenti  found,  in  his  experiments 
on  dogs,  that  the  elimination  of  indican  by  the  urine  greatly 
diminished  after  tying  the  pancreatic  passages,  but  that  it  increased 
again  when  the  animal  was  given  pancreas  peptones  or  pancreatic 
juice. 

From  the  foregoing  facts  we  conclude  that  the  products  formed 
by  the  putrefaction  in  the  intestine  are  in  part  the  same  as  those 


220  PHYSIOLOGICAL  CHEMISTRY. 

formed  by  digestion.  The  putrefaction  may  be  of  benefit  to  the 
organism  so  far  as  the  formation  of  such  products  as  albumoses, 
peptones,  and  perhaps  also  certain  amido-acids  is  concerned.  On 
the  contrary,  the  formation  of  further  splitting  products  is  to  be 
considered  as  a  loss  of  valuable  matei'ial,  and  it  is  therefore  impor- 
tant that  putrefaction  in  the  intestine  is  kept  within  certain 
limits.  If  an  animal  is  killed  while  digestion  in  the  intestine  is 
going  on,  the  contents  of  the  small  intestine  give  out  a  peculiar 
but  not  putrescent  odor.  Also  the  odor  from  the  contents  of  the 
large  intestine  is  far  less  offensive  than  a  putrefying  pancreas  in- 
fusion or  a  putrefying  mixture  rich  in  albumin.  From  this  we  may 
conclude  that  putrefaction  in  the  intestine  is  ordinarily  not  nearly 
so  intense  as  outside  of  the  organism. 

It  seems  thus  to  be  provided,  under  physiological  conditions, 
that  putrefaction  shall  not  proceed  too  far,  and  the  factors  which 
here  come  under  consideration  are  probably  of  different  kinds. 
Absorption  is  one  of  the  more  important  of  them,  and  it  has  been 
proved  by  actual  observation  that  the  putrefaction  increases,  as  a 
rule,  as  the  absorption  is  checked  and  fluid  masses  accumulate  in 
the  intestine.  The  character  of  the  food  also  has  an  unmistakable 
influence,  and  it  seems  as  if  a  large  quantity  of  carbohydrates  in 
the  food  acts  against  putrefaction  (Hieschler).  A  specially  strong 
action  tending  to  prevent  putrefaction  is  observed  in  the  bile.  This 
anti-putrid  action  does  not  occur  in  neutral  or  faintly-alkaline  bile, 
which  itself  easily  putrefies,  but  in  the  free  bile-acids,  especially  in 
taurocholic  acid  (Maly  and  Emich,  Lindberger).  There  is  no 
question  that  the  free  bile-acids  have  a  strong  preventive  action  on 
putrefaction  outside  of  the  organism,  and  it  is  therefore  difficult  to 
deny  such  an  action  in  the  intestine.  Notwithstanding  this  the 
anti -putrid  action  of  the  bile  in  the  intestine  is  contradicted  by 
certain  investigators  (Voit,  Eohmann). 

Biliary  fistulae  have  been  introduced  so  as  to  study  the  impor- 
tance of  the  bile  in  digestion  (Schwann,  Blondlot,  Bidder  and 
Schmidt,  and  others).  As  a  result  it  has  been  observed  that  from 
fatty  foods  an  imperfect  absorption  of  fat  regularly  takes  place, 
and  the  excrements  contain,  therefore,  an  excess  of  fat  and  have  a 
light-gray  or  pale  color.  How  long  after  the  operation  the  devia- 
tion from  the  normal  appears  depends  essentially  upon  the  char- 


DIGESTION.  221 

acter  of  the  food.  If  an  animal  is  fed  on  meat  and  fat,  then  the 
quantity  of  food  must  be  considerably  increased  after  the  operation, 
otherwise  the  animal  will  become  very  thin,  and  indeed  die  with 
symptoms  of  starvation.  In  these  cases  the  excrements  have  the 
odor  of  carrion,  and  this  was  considered  a  proof  of  the  action  of  the 
bile  in  checking  putrefaction.  The  emaciation  and  the  increased 
want  of  food  depend,  naturally,  upon  the  imperfect  absorption  of 
the  fats,  whose  high  calorific  value  is  reduced  and  must  be  replaced 
by  the  taking  up  of  larger  quantities  of  other  nutritive  bodies.  If 
the  quantity  of  proteids  and  fats  be  increased,  then  this  last,  which 
can  be  only  very  incompletely  absorbed,  accumulates  in  the  intes- 
tine. This  accumulation  of  the  fats  in  the  intestine  only  renders 
the  action  of  the  digestive  juices  on  proteids  more  diflBcult,  and 
these  last  increase  the  amount  of  putrefaction.  This  explains  the 
appearance  of  stinking  faeces,  whose  pale  color  is  not  due  to  a  lack 
of  bile-pigments,  but  to  a  surplus  of  fat  (Rohmann,  Voit).  If 
the  animal  is,  on  the  contrary,  fed  on  meat  and  carbohydrates,  it 
may  remain  quite  normal,  and  the  leading  off  of  the  bile  does  not 
cause  any  increased  putrefaction.  The  carbohydrates  may  be 
absoi'bed  unprevented  in  such  large  quantities  that  they  replace  the 
fat  of  the  food,  and  this  is  the  reason  why  the  animal  on  such  a 
diet  does  not  become  emaciated.  If  with  this  diet  the  putrefaction 
in  the  intestine  is  no  greater  than  under  normal  conditions  even 
though  the  bile  is  absent,  it  would  seem  that  the  bile  in  the  intes- 
tine exercise  no  preventive  action  on  putrefaction. 

We  fnust  remember,  however,  that  the  presence  of  free  acids 
counteracts  putrefaction,  and  further  that  the  carbohydrates  yield 
free  acids  by  acid  fermentation  within  the  intestine.  It  is  there- 
fore conceivable  that  to  the  carbohydrates,  which,  according  to 
HiKSCHLER,  are  capable  of  checking  putrefaction  without  entering 
into  an  acid  fermentation,  the  antiseptic  action  of  the  bile  is  due. 
It  cannot  be  denied  that  the  bile  under  ordinary  conditions,  with  a 
mixed  diet  deficient  in  carbohydrates,  has  a  preventive  action  on 
the  putrefaction  in  the  intestine.  Limboueg  has  shown  that  it 
acts  in  an  antiseptic  sense,  so  that  the  decay  of  the  proteids,  giv- 
ing rise  to  simpler  products  less  valuable,  or  perhaps  even  injurious, 
in  the  organism,  are  checked. 

Although  the  question  how  the  putrefactive  processes  in  the 


223  PHTSIOLOOICAL   CHEMISTRY. 

intestine  under  physiological  conditions  are  kept  within  certain 
limits  cannot  be  answered  positively,  still  it  may  be  asserted 
that  the  acid  reaction  of  the  upper  parts  of  the  intestine 
and  the  absorption  of  water  in  the  lower  parts  are  important 
factors. 

Excrements.  It  is  evident  that  the  residue  which  remains  after 
completed  digestion  and  absorption  in  the  intestine  must  be  differ- 
ent, both  qualitatively  and  quantitatively,  according  to  the  variety 
and  quantity  of  the  food.  In  man  the  quantity  of  excrement  from 
a  mixed  diet  is  120-150  grms.,  with  30-37  grms.  solids,  per  34 
hours,  while  the  quantity  from  a  vegetable  diet,  according  to  Voit, 
was  333  grms.,  with  75  grms.  solids.  With  a  strictly  meat  diet  the 
excrements  are  scanty,  pitch-like,  and  colored  nearly  black  by 
hsematin  and  iron  sulphide.  The  scanty  excrements  in  starvation 
have  a  similar  appearance.  A  large  quantity  of  coarse  bread  yields 
a  great  amount  of  light-colored  excrement.  If  there  is  a  large 
proportion  of  fat,  it  takes  a  lighter,  clayey  appearance.  The  decom- 
position products  of  the  bile-pigments  seem  to  play  only  a  small 
part  in  the"  normal  color  of  the  faeces. 

The  constituents  of  the  faeces  are  of  different  kinds.  We  find 
in  the  excrements  digestible  or  absorbable  constituents  of  the  food, 
such  as  muscular  fibres,  connective  tissues,  lumps  of  casein,  grains 
of  starch,  and  fat  which  have  not  had  sufficient  time  to  be  com- 
pletely digested  or  absorbed  in  the  intestinal  tract.  In  addition 
the  excrements  contain  indigestible  bodies,  such  as  remains  of 
plants,  keratin  substances,  nuclein,  and  others;  also  form-dlements 
originating  from  the  mucous  coat  and  the  glands ;  constituents  of 
the  different  secretions,  such  as  mucin,  cholalic  acid,  dyslysin,  and 
cliolesterin ;  mineral  bodies  of  the  food  and  the  secretions;  and 
lastly,  products  of  putrefaction  or  of  the  digestion,  such  as  skatol, 
indol,  volatile  fatty  acids,  lime,  and  magnesia  soaps.  Occasionally, 
also,  parasites  of  different  kinds  occur ;  and  lastly,  the  excrements 
contain  micro-organisms,  fungi  of  different  kinds,  sometimes  in 
such  large  quantities  that  the  chief  mass  of  the  excrements  seems 
to  consist  of  micro-organisms  (v.  Jaksch). 

The  reaction  of  the  excrements  is  very  changeable.  It  is  often 
A,cid  in  the  inner  part,  while  the  outer  layers  in  contact  with  the 
mucous  coat  have  an  alkaline  reaction.     In  nursing  infants  it  is 


DIGESTION.  223 

habitually  acid  (Wegscheidee).  The  odor  is  perhaps  chiefly  due 
to  skatol,  which  was  first  found  in  the  excrements  by  Bkieger, 
and  so  named  by  him.  Indol  and  other  substances  also  take  part 
in  the  production  of  odor.  The  color  is  ordinarily  lighter  or 
darker  brown,  and  depends  above  all  upon  the  nature  of  the  food. 
Medicinal  bodies  may  give  the  faeces  an  abnormal  color.  The  ex- 
crements are  colored  black  by  iron  and  bismuth,  yellow  by  rhubarb, 
and  green  by  calomel.  This  last-mentioned  color  was  formerly 
accounted  for  by  the  formation  of  a  little  mercury  sulphide,  but 
now  it  is  said  that  calomel  checks  the  putrefaction  and  the  decom- 
position of  the  bile-pigmeuts,  so  that  a  part  of  the  bile-pigments 
pass  into  the  faeces  as  biliverdin.  According  to  Lesage,  a  green 
color  of  the  excrements  in  children  is  caused  partly  by  biliverdin  and 
partly  by  a  pigment  produced  from  a  bacillus.  In  the  yolk-yellow 
or  greenish-yellow  excrements  of  nursing  infants  we  can  detect 
bilirubin.  Neither  bilirubin  nor  biliverdin  seems  to  exist  in  the 
excrements  of  mature  persons  under  normal  conditions.  On  the 
contrary,  we  find  stercobilin"  (Masius  and  Van^lair),  which,  ac- 
cording to  certain  investigators,  is  identical  Avith  hydrobilirubin 
(Malt),  which  is  obtained  from  bilirubin  by  a  reduction  process, 
and  urobilin  (Jafee) — a  view  contested  by  MacMunn".  Bilirubin 
may  occur  in  pathological  cases  in  the  fseces  of  mature  persons. 
It  has  been  observed  in  a  cr5^stallized  state  (as  hgematoidin)  in  the 
faeces  of  children  as  well  as  of  grown  persons  (Uffelmann",  v. 
Jaksch). 

The  absence  of  bile  (acholic  faeces)  causes  the  excrements  to 
have,  as  above  stated,  a  gray  color,  due  to  large  quantities  of  fat; 
this  may,  however,  be  partly  attributed  to  the  absence  of  bile-pig- 
ments. In  these  cases  a  large  quantity  of  crystals  has  been  ob- 
served (Gerhardt,  v.  Jaksch)  which  consist  chiefly  of  magnesia 
soaps  (Oesterlen)  or  sodium  soaps  (SiADELMAifN).  Hemorrhage 
in  the  upper  parts  of  the  digestive  tract  yields,  when  it  is  not 
very  abundant,  a  dark-brown  excrement,  due  to  haematin. 

ExCRETiN,  so  named  by  Marcet,  is  a  crystalline  body  occurring  in 
human  excrement,  but  which,  according  to  Hoppe-Seyler,  is  perhaps  only 
impure  cholesterin.  Excretolic  acid  is  the  name  given  by  Marcet  to  a 
body  similar  to  oil  and  with  an  excrementiteous  odor. 

In  consideration  of  the  very  variable  composition  of  excrements  their 
quantitative  analyses  are  of  little  value  and  therefore  will  be  omitted. 


224  .  PHYSIOLOGICAL   CHEMISTRY. 

Meconium  is  a  dark  brownish-green,  pitchy,  mostly  acid  mass 
without  any  strong  odor.  It  contains  greenish-colored  epithelium 
cells,  cell-detritus,  numerous  fat-globules,  and  cholesterin  plates. 
The  amount  of  water  and  solids  is  respectively  720-800  and  280- 
200  p.  m.  Among  the  solids  we  find  mucin,  bile-pigments  and 
bile-acids,  cholesterin,  fats,  soaps,  calcium  and  magnesium  phos- 
phates. Sugar  and  lactic  acid,  albuminous  bodies  (?)  and  peptones, 
also  leucin  and  tyrosin  and  the  other  products  of  putrefaction 
occurring  in  the  intestine  are  absent.  Meconium  may  contain 
undecomposed  taurocholic  acid,  bilirubin  and  biliverdin,  but  it 
does  not  contain  any  hydrobilirubin,  which  is  considered  as  proof 
of  the  non-existence  of  putrefactive  processes  in  the  digestive  tract 
of  the  foetus. 

In  medico-legal  cases  it  is  sometimes  necessary  to  decide  whether 
spots  on  linen  or  other  substances  are  caused  by  meconium.  In 
such  cases  we  have  the  following  conditions.  The  spot  caused  by 
meconium  has  a  brownish-green  color  and  can  be  easily  separated 
from  the  material  because,  on  account  of  the  ropy  property  of  the 
meconium,  it  is  difficult  to  wet  through.  When  moistened  with 
water  it  does  not  develop  any  special  odor,  but  on  warming  with 
dilute  sulphuric  acid  it  has  a  somewhat  fetid  odor.  It  forms  with 
water  a  slimy,  greenish-yellow  liquid  containing  brown  flakes.  The 
solution  gives  with  an  excess  of  acetic  acid  an  insoluble  precipitate 
of  mucin  ;  on  boiling  it  does  not  coagulate.  The  filtered,  watery 
extract  gives  GMELiisr^s,  but  still  better  Huppekt's,  reaction  for 
bile-pigments.  The  liquid  precipitated  by  an  excess  of  milk  of 
lime  gives  a  nearly  colorless  filtrate,  which  after  concentration  gives 
Pettenkofer's  reaction. 

Tlie  contents  of  the  intestine  under  abnortnal  conditions  are  per- 
haps less  the  subject  of  chemical  analysis  than  of  an  inspection  or 
microscopical  investigation.  On  this  account  the  question  as  to 
tlie  properties  of  the  contents  of  the  intestine  in  different  diseases 
cannot  be  thoroughly  treated  here.  The  question  as  to  the  differ- 
ent processes  which,  so  far  as  they  are  dependent  on  secretion  and 
absorption,  cause  an  abnormal  consistency,  a  thinning  of  the  excre- 
ments, possesses  a  certain  interest.  Such  excrements  may  in  part  be 
produced  by  arrested  absorption  of  liquid  from  the  intestine  for 
some  reason  or  other,  and  in  part  caused  by  an  increased  secre- 
tion or  a  transudation  of  liquids  into  the  intestine. 


DIGESTION.  225 

A  diminished  absorption  (of  water)  may  be  caused  by  a  more 
active  movement  of  the  intestine,  which  causes  their  contents  to 
pass  quickly,  and  in  this  way  the  action  of  hixatives  is  often  ex- 
plained. A  diminished  absorption  may  also  be  due  to  a  decreased 
activity  of  the  absorbing  cells.  In  absorption,  which  is  generally 
accepted  to-day,  the  cells  of  the  mucous  coat  take  an  active  part, 
and  anything  which  acts  disturbingly  on  the  protoplasm  of  these 
cells  must  also  exercise  an  influence  on  the  absorption.  This  coji- 
dition  with  regard  to  the  action  of  laxatives  has  been  especially 
noted  by  Hoppe-Seylek.  According  to  him,  it  is  also  probable 
that  such  laxatives,  of  which  only  traces  are  required  for  absorption, 
by  a  direct  action  on  the  intestinal  epithelium — whether  the  absorp- 
tion is  made  more  difficult,  or  a  transudation  made  possible,  or 
whether  the  action  of  these  two  is  simultaneous — cause  watery 
evacuations.  According  to  Rohmann,  concentrated  salt  solutions 
act  by  a  decreased  absorption  activity. 

A  thin  evacuation  may  be  produced  by  an  increased  elimination 
of  fluid  into  the  intestine,  and  there  are  many  investigators  who 
consider  it  positively  proved  that  a  transudation  of  liquid  into  the 
intestine  is  caused  by  the  action  of  saline  laxatives. 

The  character  of  the  intestinal  epithelium  is  undoubtedly  an 
important  factor  in  the  production  of  such  a  transudation,  and 
when  this  is  caused  by  the  saline  laxatives  it  probably  is  produced 
by  action  on  the  epithelium.  We  must  admit  with  Hoppe-Seyler 
and  other  investigators  that  the  most  important  regulator  of  the 
flow  of  liquid  through  the  intestinal  mucous  membrane  is  the 
intestinal  epithelium.  It  is  the  epithelium  which  renders  possible 
the  stream  of  fluid  contrary  to  the  laws  of  osmose,  and  which 
under  normal  conditions  prevents  a  transudation  into  the  intes- 
tines. Bodies  which  affect  the  epithelium  may  therefore  cause  a 
transudation,  and  this  is  found  to  be  especially  abundant  after 
ejection  of  the  intestinal  epithelium.  The  most  striking  example 
of  this  is  observed  in  Asiatic  cholera,  in  which  the  epithelium  is 
largely  expulsed  and  an  extraordinarily  abundant  transudation 
takes  place. 


226  PHYSIOLOGICAL  CHEMISTRY. 


Appendix.     Intestinal  Concrements. 

Calculi  occur  very  seldom  in  human  intestine  or  in  the  intestine 
of  carnivora,  but  they  are  quite  common  in  herbivora.  Foreign 
bodies  or  indigested  residues  of  food  may,  when  for  some  reason  or 
other  they  are  retained  in  the  intestine  for  some  time,  become 
incrusted  with  salts,  especially  ammonium-magnesium  phosphate 
or  magnesium  phosphate,  and  these  salts  form  usually  the  chief 
constituent  of  the  concrements.  In  man  they  are  sometimes  oval 
or  round,  yellow,  yellowish-gray,  or  brownish-gray,  of  variable  size, 
consisting  of  concentric  layers  and  containing  chiefly  ammonium- 
magnesium  phosphate,  calcium  phosphate,  besides  a  small  quantity 
of  fat  or  pigment.  The  nucleus  ordinarily  consists  of  some  foreign 
body,  such  as  the  stone  of  a  fruit,  a  fragment  of  bone,  or  something 
similar.  In  those  countries  where  bread  made  from  oat-bran  is  an 
important  food,  we  often  find  in  the  large  intestine  balls  similar 
to  the  so-called  hair-balls  (see  below).  Such  calculi  contain  calcium 
and  magnesium  phosphate  (about  70^),  oat-bran  (15-18^),  soaps 
and  fat  (about  10^).  Concretions  which  contain  very  much  (about 
74^)  fat  occur  seldom,  and  those  consisting  of  fibrin  clots,  sinews, 
or  pieces  of  meat  incrusted  with  phosphates  are  also  rare. 

Intestinal  calculi  occur  often  in  animals,  especially  in  horses  fed 
on  bran.  These  calculi,  which  attain  a  very  large  size,  are  hard 
and  heavy  (as  much  as  8  kilos)  and  consist  in  great  part  of  concen- 
tric layers  of  ammonium-magnesium  phosphate.  Another  variety 
of  concrements  which  occurs  in  horses  and  cattle  consists  of  gray 
colored,  often  very  large,  but  relatively  light  stones  which  contain 
plant-remains  and  earthy  phosphates.  Stones  of  a  third  variety 
are  sometimes  cylindrical,  sometimes  spherical,  smooth,  shining, 
brownish  on  the  surface,  consisting  of  matted  hairs  and  plant- 
fibres,  and  termed  hair-halls.  The  so-called  "  ^gagropila,"  which 
probably  originate  from  the  AifTiLOPUS  rupicapra,  belong  to  this 
group,  and  they  are  generally  considered  as  nothing  else  than  the 
hair-balls  of  cattle. 

The  so-called  oriental  hezoar-stone  belongs  also  to  the  intestinal 
concrements,  and  probably  originates  from  the  capra  ^gagrus 
and  ANTILOPE   DORCAS.     We  may  have  two  varieties  of  bezoar- 


DIGESTION.  227 

stones.  One  is  olive-green,  faintly  shining,  formed  of  concentric 
layers.  On  heating  it  melts  with  the  development  of  an  aromatic 
odor.  It  contains  as  chief  constituent  lithofellic  acid,  CjoHagO^ , 
which  is  related  to  cholalic  acids,  and  besides  this  a  bile-acid, 
LiTHOBiLic  ACID.  The  Others  are  nearly  blackish  brown  or  dark 
green,  very  glossy,  consisting  of  concentric  layers,  and  do  not  melt 
on  heating.  They  contain  as  chief  constituent  ellagic  acid,  a  de- 
rivative of  tannic  acid,  of  the  formula  CuHgOg,  which  gives  a  deep 
blue  color  with  an  alcoholic  solution  of  ferric  chloride.  This  last- 
mentioned  bezoar-stone  originates,  to  all  appearances,  from  the 
food  of  the  animal. 

Ambergris  is  generally  considered  an  intestinal  concrement  of  the  sperm- 
whale.  Its  chief  constituent  is  ambkain,  which  is  a  non-nitrogenious  sub- 
stance perhaps  related  to  cholesterin.  Ambrain  is  insoluble  in  water  and  is 
not  changed  by  boiling  alkalies.     It  dissolves  in  alcohol,  ether,  and  oils. 

VI.  Absorption. 

In  discussing  the  absorption  processes  we  must  treat  of  the 
form  into  which  the  different  foods  are  transformed  before  absorp- 
tion, of  the  manner  in  which  this  is  accomplished,  and,  lastly,  of  the 
force  which  acts  in  these  processes. 

Starch  and  the  other  carbohydrates  are  chiefly  absorbed  as  sugar, 
in  part  also  as  organic  acids  (lactic  acid),  and  perhaps  in  small 
quantities  as  dextrin.  Fats  may  indeed  be  partly  absorbed  as 
soaps;  still  the  quantity  absorbed  in  this  way  is  very  small  compared 
with  that  absorbed  as  an  emulsion.  Emulsion  is  undoubtedly  the 
most  important  form  under  which  fat  is  absorbed,  and  the  neutral 
fats,  also  the  free  fatty  acids,  are  emulsified  when  they  occur  in 
large  quantities  in  the  intestines. 

Peptone,  as  above  stated,  is  the  final  product  of  the  digestion  of 
albuminous  bodies.  Xow  as  peptone  is  a  very  soluble  and  a  rela- 
tively easily  diffusible  modification  of  proteids,  it  is  not  difficult  to 
admit  the  deduction  that  proteids  must  be  changed  into  peptone 
in  order  that  it  may  be  readily  absorbed.  Certain  observations  of 
FuxKES  on  animals  confirm  this  view.  He  found  in  an  untied 
intestinal  knot  of  a  living  animal  that  the  peptone  (in  the  old 
sense  of  the  word)  was  absorbed  considerably  faster  than  other 
proteids.     There  is  also  no  doubt  that  a  part  of  the  proteids  is 


228  PHTSIOLOOICAL   CHEMI8TRT, 

invariably  absorbed  from  the  intestinal  canal  as  peptones,  or  more 
correctly  perhaps  as  albumoses  and  peptones.  But  it  has  been 
positively  settled  by  the  investigations  of  Beucke,  Bauer  and 
VoiT,  EiCHHOEST,  CzERNY  and  Latsche]s-berger,  that  peptonized 
albumin,  casein,  myosin,  and  alkali  albuminates  cannot  be  ab- 
sored  from  the  intestines — a  matter  which  is  of  practical  import- 
ance, especially  with  regard  to  the  nutritive  clysters.  If  the 
albumin  can  be  absorbed  partly  as  such  and  partly  as  peptone,  then 
the  question  arises,  how  much  more  can  it  be  absorbed  in  one  form 
than  in  the  other  ?  This  question  cannot  be  decisively  answered. 
The  investigations  by  Schmidt-Mulheim  of  the  contents  of  the 
stomach  and  intestine  of  dogs  show  that  the  stomach  contains  a 
considerably  larger  amount  of  peptone  than  of  simple  dissolved 
proteids,  wbich  seems  to  indicate  that  the  greatest  part  of  the  pro- 
teids  is  absorbed  as  peptones  (or  albumoses). 

The  soluble  salts  are  also  absorbed  with  the  water.  The  albu- 
min and  peptone  which  can  dissolve  a  considerable  quantity  of 
salts  insoluble  in  alkaline  water  are  of  great  importance  in  the  ab- 
sorption of  such  salts. 

The  soluble  constituents  of  the  digestive  secretions  may,  like 
other  dissolved  bodies,  be  absorbed,  as  is  demonstrated  by  the  pas- 
sage of  peptone  into  urine  ;  the  enzymes  may  also  be  absorbed. 
The  occurrence  of  urobilin  in  urine  attests  to  the  absorption  of  the 
bile-constituents  under  physiological  conditions  notwithstanding 
that,  according  to  certain  investigators  (MAcMuiTN),  it  is  not 
identical  with  hydrobilirubin,  and  contrariwise,  according  to  the 
observations  of  Copemaf  and  Winston  on  a  woman  with  a  biliary 
fistula,  it  also  occurs  in  the  urine  when  no  bile  comes  into  the 
intestine.  The  question  as  to  the  occurrence  of  very  faint  traces 
of  bile-acids  in  normal  urine  is  also  contradicted,  and  from  the 
behavior  of  the  urine  it  is  therefore  difiicult  to  draw  any  positive 
conclusion  as  to  a  possible  absorption  of  the  bile-constituents  from 
the  intestine.  On  the  other  hand,  the  absorption  of  bile-acids 
from  the  intestine  seems  to  be  established  by  other  observations. 
Tappeiner  introduced  a  solution  of  bile-acid  salts  of  a  known 
concentration  into  an  untied  intestinal  knot,  and  after  a  time 
investigated  the  contents.  He  found  that  in  the  jejunum  and  the 
ileum,  but  not  in  the  duodenum,  an  absorption  of  bile-acids  took 


DIGESTION.  229 

place,  and  further  that  of  the  two  bile-acids  only  the  glycocholic 
acid  was  absorbed  in  the  jejunum.  Further,  Schiff  long  ago 
expressed  the  opinion  that  bile  undergoes  an  intermediate  circula- 
tion, in  such  wise  that  it  is  absorbed  from  the  intestine,  then 
carried  to  the  liver  by  the  blood,  and  lastly  eliminated  from  the 
blood  by  this  organ.  Although  this  view  has  met  with  some  oppo- 
sition, still  its  correctness  seems  to  be  established  by  the  researches 
of  various  investigators,  and  more  recently  by  Pkevost  and  Bixet, 
at  least  to  the  extent  that  after  the  introduction  of  foreign  bile 
into  the  intestine  of  an  animal  the  foreign  bile-acids  appear  again 
in  the  secreted  bile. 

There  are  two  possible  ways  in  which  the  absorbed  bodies  may 
enter  the  blood-stream.  They  may  pass  into  the  blood  through 
the  chylous  vessels  and  the  thoracic  duct  indirectly,  or  they  may, 
after  they  have  passed  the  intestinal  epithelium,  pass  into  the 
blood-capillaries  of  the  villous  membranes  and  so  directly  into  the 
blood.  By  the  investigations  of  Ludwig  and  his  pupils,  Eohrig, 
Zawilsky,  v.  Mering  and  Schmidt-Mulheim,  as  well  as  by  those 
of  Heideisthain  and' his  jAipils,  it  has  now  been  proved  that  the 
fat  is  driven  through  the  chylous  vessels  and  the  thoracic  duct  to 
the  blood,  while  on  the  contrary  the  bodies  soluble  in  water,  such  as 
sugar  and  salts,  are  taken  up  by  the  blood  of  the  capillaries  of  the 
villous  membrane  and  in  this  way  pass  into  the  blood.  The  reason 
•why  the  dissolved  bodies  do  not  pass  into  the  chylous  vessels  in 
larger  quantities  is  explained  by  Heidenhaix  to  lie  in  the  anatomi- 
cal situation, — the  arrangement  of  the  capillaries  close  under  the 
layer  of  epithelium.  Ordinarily  these  capillaries  find  the  necessary 
time  for  the  taking  up  of  the  water  and  the  solids  dissolved  in  it. 
But  Avhen  a  large  quantity  of  liquid,  such  as  a  sugar  solution,  is 
introduced  into  the  intestine  at  once,  this  is  not  possible,  and  in 
these  cases  a  part  of  the  dissolved  bodies  pass  into  the  chylous 
vessels  and  the  thoracic  duct  (Gin^sberg  and  Eohmaxn). 

The  question  of  the  absorption  of  the  peptones,  albeit  in  most 
cases  these  have  not  been  differentiated  from  albumoses,  has  been 
the  subject  of  numerous  investigations.  Ludwig  and  Schmidt- 
Mulheim  tied  the  jugular  and  humeral  arteries  and  lymphatic 
vessels  of  both  sides  of  a  dog  so  that  the  section  showed  later  a 
complete  cutting  off  of  the  chyle  from  the  blood-circulation.     They 


230  PHYSIOLOGICAL   CHEMISTRY. 

found  that  the  absorption  of  proteids  from  the  intestine  was  not 
influenced  thereby,  and  from  this  concluded  that  the  proteids  as 
well  as  the  other  nutritive  bodies  soluble  in  water  pass  directly 
into  the  blood  through  the  walls  of  the  intestinal  capillaries.  If 
this  were  the  case,  then  we  might  expect  to  find  peptone  in  solution 
in  the  blood  during  or  after  digestion.  This,  however,  is  not  the 
case.  ScHMiDT-MiJLHEiM  and  Hofmeistee  found  only  traces  of 
peptone  in  serum  or  blood,  and  according  to  NEiJMEiSTER  it  does 
not  occur  even  as  traces.     Chyle  does  not  contain  any  peptone. 

Then  where   does   the  peptone   which  is  absorbed  from  the 
intestine  remain?     If  peptone  in  solution  is  introduced  into  the 
circulating  blood,  it  is  quickly  eliminated  therefrom  with  the  urine 
(Plos'z  and  Gyergtai,  Hofmeister,  Schmidt-Mtjlheim).     The 
same  happens  also  after  injecting  peptone  subcutaneously.     Nor- 
mal urine  does  not  contain  any  peptone,  and  the  absence  of  this 
body  in  the  blood  after  digestion  cannot  be  explained  by  assuming 
that  it  is  eliminated  by  the  kidneys.    Since  the  peptone  introduced 
into  the  blood  is  quickly  eliminated  by  the  kidneys,  while  the 
peptone  formed  in  the  intestine  does  not  pass  into  the  urine,  it 
may  perhaps  be  thought  that  this  peptone  is  retained  normally  by 
the  liver  and  is  absorbed,  and  only  that  peptone  which  finds  its 
way  into  the  circulating  blood  by  evasion  from  this  organ  passes 
into  the  urine.      This  supposition,  however,  is  untenable.     Neu- 
meister  has  investigated   the   portal  blood  of  rabbits  in  whose 
stomachs  large  quantities   of  albumoses   and  peptones  had  been 
introduced,  and  found  therein  only  traces  of  the  body  in  question. 
He  has  also  shown  that  when  we  supply  the  liver  of  a  dog  with 
the  portal-blood  peptone  (ampho-peptone),  this  is  not  retained  by 
the  liver  but  is  eliminated  with  the  urine.     Peptone  seems  to  pass 
neither  into  the  blood  nor  the  chylous  vessels,  but  to  be  changed 
in  some  way  by  the  walls  of  the  intestine.     Hofmeister,  according 
to  whom  the  walls  of  the  stomach  and  the  intestine  are  the  only 
parts  of  the  body  in  which  peptones  occur  constantly  during  diges- 
tion, has  also  made  the  observation  that  peptone  (at  the  tempera- 
ture of  the  body)  after  a  time  disappeared  from  the  excised  but 
apparently  still  living  mucous  coat  of  the  stomach.     Peptone  seems 
to  undergo  a  change  in  the  mucous  membrane  of  the   digestive 
canal,  and  the  following  observation   of   Ludwig   and   Salvioli 


DIGESTION.  231 

bears  out  that  assumption.  These  investigators  introduced  a 
peptone  solution  into  a  doubly-tied,  removed  knot  of  the  small 
intestine  which  was  kept  active  by  passing  through  defibrinated 
blood,  and  observed  that  the  peptone  disappeared  from  the  intes- 
tine, but  that  the  blood  passing  through  did  not  contain  any  pep- 
tone. 

If,  then,  peptone  already  disappears  in  the  mucous  coat,  or  at 
least  in  the  walls  of  the  digestive  tract,  the  question  naturally 
arises,  what  becomes  of  the  peptone  in  the  mucous  membrane  ? 
The  experiments  of  Malt,  Plos'z  and  Gyergyai,  Adamkiewicz, 
ZuNTz  and  Pollitzer  have  established  that  the  albumoses  and 
peptones  may  be  substituted  for  albumin  in  the  food,  and  may  also 
be  converted  into  ordinary  albumin.  We  must  then  assume  that 
peptone  is  already  converted  into  albumin  in  the  mucous  mem- 
brane of  the  digestive  canal. 

According  to  Hofmeister,  a  considerable  increase  of  leucocytes 
occurs  in  the  adenoid  tissues  during  digestion,  an  observation 
which  is  in  close  accord  with  that  of  Pohl,  who  found  that  in 
dogs  kept  on  an  albuminous  diet  the  venous  blood  of  the  intestine 
contains  more  leucocytes  than  the  arterial  blood.  According  to 
Hofmeister,  leucocytes  play  an  important  part  in  the  absorption 
and  assimilation  of  the  peptones.  They  may  take  up  the  peptones 
and  be  the  means  of  transporting  them  to  the  blood,  and  secondly 
by  their  growth,  regeneration,  and  increase  may  stand  in  close  rela- 
tion to  the  transformation  and  assimilation  of  the  peptones. 
Heidenhaik,  who  considers  that  the  transformation  of  peptone 
into  albumin  in  the  mucous  membrane  is  positively  settled,  does 
not,  attribute  so  great  an  importance  to  these  last  in  the  absorption 
of  the  peptones  as  Hofmeister,  chiefly  on  the  ground  of  equaliza- 
tion of  the  quantity  of  absorbed  peptones  and  leucocytes.  He  con- 
siders it  most  probable  that  the  reconversion  of  the  peptones  into 
albumin  takes  place  in  the  epithelium  layers. 

Little  is  known  concerning  the  forces  taking  part  in  absorption. 
Osmose  and  filtration  were  formerly  considered  as  the  most  impoi"- 
tant  factors.  But  as  in  regard  to  the  peptones,  whose  formation 
in  the  digestion  was  considered  as  taking  place  especially  in  the 
interest  of  a  facilitated  osmosis  and  filtration,  but  whose  conditions 
have  been  found  quite  different  and  much  more  complicated,  so  in 


232  PHY8I0L00ICAL   CHEMISTRY. 

the  absorption  theory  there  is  a  still  greater  contrast  between 
former  and  present  views,  the  latter  inclining  to  the  theory  that 
absorption  is  a  process  connected  with  the  vital  properties  of  the 
cells.  Investigations  in  this  direction  have  been  made  by  Heiden- 
HAiN  and  his  pupils,  Eohmann  and  G-umilewsky;  and  these 
investigations  have  shown  that  the  cells  take  an  active  part  in  the 
absoi-ption,  and  that  this  action  is  independent  of  the  processes 
caused  by  an  unequal  diffusibility  of  the  different  bodies.  For 
example,  in  a  solution  which  contains  equal  quantities  of  grape- 
sugar  and  sodium  sulphate  the  sugar  will  be  almost  completely 
absorbed  in  a  certain  time,  while  the  salt,  which  has  the  greater 
diffusibility,  still  remains  in  considerable  amounts  in  the  intestine. 
Certain  coloring  matters  are  not  absorbed,  and  the  cells  seem  to 
have  the  property  of  discriminating  between  the  different  sub- 
stances. The  absorption  of  dissolved  bodies  seems  to  be  connected 
with  a  specific  activity  of  the  living  cell,  the  living  protoplasm. 

In  the  absorption  of  bodies  not  dissolved,  of  the  emulsified  fats 
forces  take  part  which  are  not  known.  That  the  bile  performs 
the  most  important  part  in  the  absorption  of  fats  is  very  generally 
admitted,  but  how  the  bile  acts  in  this  process  is  not  yet  deter- 
mined. V.  WiSTHSTGHAUSEN"  has  found  that  fat  rises  higher  in  a 
capillary  tube  when  it  has  been  moistened  with  bile  than  when 
with  water,  and  further  that  fluid  fat  filters  more  easily  through  a 
dead  membrane  dipped  in  bile  than  when  dipped  in  water.  From 
these  observations,  whose  correctness  has  lately  been  disputed  by 
Gad  and  Gropee,  the  inference  has  been  drawn  that  bile  facilitates 
the  capillary  attraction  and  thereby  accelerates  the  absorption  of  the 
fats.  The  epithelium  layer  of  the  intestinal  mucous  membrane 
cannot  be  compared  with  a  dead  membrane  soaked  in  water,  and  it 
is  therefore  doubtful  if  the  above-mentioned  action  of  bile  can  have 
any  influence  on  the  absorption  of  fats  in  the  intestine.  That  the 
absorption  of  fats  is  caused  by  the  lymphoidal  migratory  cells 
{Zawartkin;  ScHiEFFER)  is  disputed  by  Grueisthagen"  and 
Heidenhain.  According  to  them,  the  fat  takes  its  way  chiefly 
through  the  epithelium  cells.  How  these  last  act  is,  like  the 
nature  of  the  action  in  absorption,  enveloped  in  darkness. 


CHAPTER  VIIL 
TISSUES  OF  THE  CONNECTIVE   SUBSTANCE. 

I.  The  Connective  Tissues. 

The  form-elements  of  the  typical  connective  tissues  are  cells  of 
various  kinds,  of  a  not  very  well  known  chemical  composition,  and 
gelatine-yielding  fibrils.  Besides  these,  elastic  formations  are  often 
found  in  variable  amounts,  though  sometimes  in  sucli  predominant 
quantities  that  the  connective  tissue  passes  nearly  into  an  elastic 
tissue.  Mucin  is  also  found  in  the  connective  tissue,  serum 
globulin  and  serum  albumin  occurring  in  the  parenchymatous  fluid 
(Loebisch). 

If  finely-divided  tendons  are  extracted  in  cold  water,  the  albu- 
minous bodies  soluble  in  the  nutritive  fluid  in  addition  to  a  little 
mucin  are  dissolved.  If  the  residue  is  extracted  with  half-satu- 
rated lime-water,  then  the  mucin  is  dissolved  (Rollett,  Loebisch) 
and  may  be  precipitated  from  the  filtered  extract  by  saturating 
with  acetic  acid.  The  digested  residue  contains  the  fibrils  of  the 
connective  tissue  together  with  the  cells  and  the  elastic  substance. 

The  fibrils  of  the  connective-tissue  consist  of  collagen.  They 
are  elastic,  swell  slightly  in  water,  somewhat  more  in  diluted 
alkalies  or  acetic  acid,  but  on  the  other  hand  are  shrivelled  by 
the  action  of  certain  metallic  salts,  such  as  ferrous  sulphate  or 
mercuric  chloride,  and  by  the  action  of  tannic  acid,  which  forms 
with  collagen  an  insoluble  combination.  Among  these  combina- 
tions, which  prevent  the  putrefaction  of  collagen,  that  with  tannic 
acid  has  been  found  of  great  value  in  the  preparation  of  leather. 
In  regard  to  tendon  mucin  see  page  32,  and  in  regard  to  collagen, 
glutin,  and  elastin  see  pages  36-38. 

283 


234  PHYSIOLOGICAL   CHEMISTRY. 

The  tissues  described  under  the  names  mucous  or  gelatinous 
tissues  are  characterized  more  by  their  physical  than  their  chemical 
properties  and  have  been  but  little  studied.  So  much,  however,  is 
known,  that  the  mucous  or  gelatinous  tissues  contain,  at  least  in 
certain  cases,  as  in  the  acaleplise,  no  mucin. 

The  umbilical  cord  is  the  most  accessible  material  for  the  inves- 
tigation of  the  chemical  constituents  of  the  gelatinous  tissues. 
The  mucin  occurring  therein  has  been  described  on  page  33.  C. 
Th.  Morker  has  found  a  mucoid  in  the  vitreous  humor  which 
contains  13.20^  nitrogen  and  1.19^  sulphur. 


II.  Cartilage. 

Cartilaginous  tissue  consists  of  cells  and  of  a  basic  substance 
originally  hyaline,  which,  however,  may  become  changed  in  such 
wise  that  there  appears  in  it  a  network  of  elastic  fibres  or  connec- 
tive-tissue fibrils. 

Those  cells  that  offer  great  resistance  to  the  action  of  alkalies 
and  acids  have  not  been  carefully  studied.  According  to  former 
views,  the  basic  substance  was  considered  as  consisting  of  a  body 
analogous  to  collagen,  the  so-called  cliondrigen,  which  under  similar 
conditions  passes,  like  collagen,  into  a  corresponding  gelatine  called 
chondrin  or  cartilage-gelatine.  The  more  recent  investigations  of 
MoROCHOV^^ETZ  and  others,  but  especially  those  of  C.  Th.  Morker, 
have  shown  that  the  basic  substance  of  the  cartilage  consists  of  a 
mixture  of  collagen  with  other  bodies. 

The  tracheal,  thyroideal,  cricoidal,  and  arytenoidal  cartilages 
of  full-grown  cattle  contain,  according  to  Morner,  four  consti- 
tuents in  the  basic  substance,  namely,  chondromucoid,  cliondroitic 
acid,  collagen,  and  albumoid. 

Chondromucoid.  This  body,  according  to  Morfer,  has  the 
composition  C  47.30,  H  6.43,  N  13.58,  S  2.43,  0  31.28  per  cent. 
Sulphur  is  in  part  loosely  combined  and  may  be  split  off  by  the 
action  of  alkalies,  and  a  part  separates  as  sulphuric  acid  when 
boiled  with  hydrochloric  acid.  Chondromucoid  is  decomposed  by 
dilute  alkalies  and  yields  alkali  albuminate,  peptone  substance, 
chondroitic  acid,  alkali  sulphides,  and  some  alkali  sulphates.     On 


TISSUES  OF  THE  CONNECTIVE  SUBSTANCE.  235 

boiling  with  acids  it  yields  acid  albuminate,  peptone  substance, 
chondroitic  acid,  and  on  account  of  the  further  decomposition  of 
this  last  body  sulphuric  acid  and  a  reducing  substance  are  formed. 

Chondromucoid  is  a  white,  amorphous,  acid-reacting  powder 
which  is  insoluble  in  water,  but  dissolves  easily  on  the  addition  of 
a  little  alkali.  This  solution  is  precipitated  by  acetic  acid  in  great  l^ 
excess  and  by  small  quantities  of  mineral  acids.  The  precipitation 
may  be  retarded  by  neutral  salts  or  by  chondroitic  acid.  The 
solution  containing  NaCl  and  acidified  with  HCl  is  not  precipitated 
by  potassium  ferrocyanide.  Precipitants  for  chondromucoid  are 
alum,  ferric  chloride,  sugar  of  lead  or  basic  lead  acetate.  Chon- 
dromucoid is  not  precipitated  by  tannic  acid,  and  it  may  by  its  ^ 
presence  prevent  the  precipitation  of  gelatine  by  this  acid.  It  gives 
the  usual  color  reactions  for  albuminous  bodies;  namely,  with 
nitric  acid,  with  copper  sulphate  and  alkali,  with  Millon's  and 
Adamkiewicz's  reagents. 

Chondroitic  Acid.  This  acid,  which  thus  far  has  not  been  ob- 
tained free,  but  as  acid  salts,  has,  according  to  Mokner.  the  follow- 
ing composition  :  C  35.28,  H  4.68,  N"  3.15,  S  6.33,  0  50.56  per  cent. 
On  boiling  with  dilute  hydrochloric  acid  all  the  sulphur  splits  off  as 
H2SO4 ,  and  a  reducing  substance  is  formed  at  the  same  time  whose 
nature  is  not  known. 

This  acid  (more  correctly  the  acid  alkali  salts)  appears  as  a 
white  amorphous  powder  which  dissolves  very  easily  in  water, 
forming  an  acid  solution  and  when  sufficiently  concentrated,  a 
sticky  liquid  similar  to  a  solution  of  gum  arable.  The  neutralized 
solution  is  precipitated  by  tin  chloride,  basic  lead  acetate,  neutral 
ferric  chloride,  and  by  alcohol  in  the  presence  of  a  little  neutral 
salt.  The  solution,  on  the  other  hand  is  not  precipitated  by  acetic 
acid,  tannic  acid,  potassium  ferrocyanide  and  acid,  sugar  of  lead, 
mercuric  chloride,  or  silver  nitrate.  Chondroitic  acid  does  not  give 
the  color  reactions  for  albuminous  bodies. 

Preparation  of  chondromucoid  and  chondroitic  acid.  If  very 
finely-cut  cartilage  is  extracted  with  Avater,  the  preformed  chon- 
droitic acid,  as  well  as  some  chondromucoid,  is  dissolved.  In  this 
watery  extract  the  chondroitic  acid  prevents  the  precipitation  of 
this  chrodromucoid  by  means  of  an  acid.  If  2-4  p.  m.  HCl  is 
added  to  this  watery  extract  and  warmed  on  the  water-bath,  the 


236  PHYSIOLOGICAL   CHEMISTRY. 

chondromucoid  gradually  separates,  while  the  chondroitic  acid  and 
the  rest  of  the  chondromucoid  remain  in  the  filtrate.  If  the  car- 
tilage, which  has  been  lixiviated,  at  the  temperature  of  the  body, 
with  water,  is  extracted  with  hydrochloric  acid  of  3-3  p.  m.  until 
the  collagen  is  converted  into  soluble  gelatine,  the  remaining  chon- 
dromucoid may  be  removed  from  the  insoluble  residue  by  dilute 
alkali  and  precipitated  from  the  alkaline  extract  by  an  acid.  It 
may  bo  purified  by  repeatedly  redissolving  in  water  with  the  aid  of 
a  little  alkali,  precipitating  by  an  acid  and  then  treating  with 
alcohol  and  ether. 

The  chondroitic  acid  originally  formed,  or  that  formed  by  the 
decomposition  of  chondromucoid,  is  obtained  by  lixiviating  the 
cartilage  with  a  5^  caustic-alkali  solution.  The  alkali  albuminate 
formed  by  the  decomposition  of  the  chondromucoid  can  be  re- 
moved from  the  solution  by  neutralization,  then  the  peptone 
precipitated  by  tannic  acid,  the  excess  of  this  acid  removed  with 
sugar  of  lead,  and  the  lead  separated  from  the  filtrate  by  HjS. 
If  further  purification  is  necessary,  the  acid  is  precipitated  with 
alcohol,  the  precipitate  dissolved  in  water,  this  solution  dialyzed 
and  precipitated  again  with  alcohol,  this  dissolving  in  water  and 
precipitating  with  alcohol  being  repeated  a  few  times,  and  lastly  the 
acid  is  treated  with  alcohol  and  ether. 

The  collagen  of  the  cartilage  gives,  according  to  Moener,  a 
gelatine  which  contains  only  16.4^  N  and  which  can  hardly  be 
considered  identical  with  ordinary  glutin. 

On  the  above-mentioned  cartilages  of  full-grown  animals  the 
chondroitic  acid  and  chondromucoid,  perhaps  also  the  collagen, 
are  found  surrounding  the  cells  as  round  balls  or  lumps.  These 
balls  (Morner's  cliondrin-halls),  which  give  a  blue  color  with 
methyl- violet,  lie  in  the  meshes  of  an  albumoid  structure,  which  is 
colored  when  brought  in  contact  with  tropgeolin. 

This  albumoid  is  a  nitrogenized  body  which  contains  loosely- 
combined  sulphur.  It  is  soluble  with  difficulty  in  acids  and  alka- 
lies, and  resembles  keratin  in  many  respects,  but  differs  from  it  by 
being  soluble  in  gastric  juice.  In  other  respects  it  is  more  similar 
to  elastin,  but  differs  from  this  substance  by  containing  sulphur. 
This  albumoid  gives  the  color  reactions  of  the  albuminous  bodies. 

The  preparation  of  cartilage-gelatine  and  albumoid  may  be  per- 
formed according  to  the  following  method  of  Morner.  First  re- 
move the  chondromucoid  and  chondroitic  acid  by  extraction  with 
dilute  caustic  potash   (0.2-0.5^),  remove  the  alkali  from   the  re- 


TISSUES  OF  THE  CONNECTIVE  SUBSTANCE.  287 

maining  cartilage  by  water,  and  then  boil  with  water  in  a  Papin's 
digester.  The  collagen  passes  into  solution  as  gelatine,  while  the 
albumoid  remains  undissolved  (contaminated  by  the  cartilage-cells). 
The  gelatine  may  be  purified  by  precipitating  with  sodium  sul- 
phate, which  must  be  added  to  saturation  in  the  faintly-acidified 
solution,  redissolving  the  precipitate  in  water,  dialyzing  well,  and 
precipitating  with  alcohol. 

According  to  Mokker,  no  albumoid  is  found  in  young  car- 
tilage, but  only  the  three  first-mentioned  constituents.  Neverthe- 
less the  young  cartilage  contains  about  the  same  amounts  of  nitrogen 
and  mineral  substances  as  the  old. 

Hoppe-Seyler  found  in  fresh  rib  cartilage  676. 7  p.  m.  water, 
301.3  p.  m.  organic  and  22  p.  m.  inorganic  substance.  In  the 
cartilage  of  the  knee-joint  735.9  p.  m.  water,  248.7  p.  m.  organic 
and  15.4  p.  m,  inorganic  substance  have  been  found.  The  ash  of 
cartilage  contains  considerable  amounts  (even  800  p.  m. )  of  alkali 
sulphate,  which  probably  did  not  exist  originally  as  such,  but  is 
produced  in  great  part  by  the  calcining  of  the  ciiondroitic  acid  and 
the  chondromucoid.  The  analyses  of  the  ash  of  cartilage  therefore 
cannot  give  a  correct  idea  of  the  quantity  of  mineral  bodies  exist- 
ing in  this  substance.  Petersen  and  Soxhlet  have  found  940 
p.  m.  NaCl  in  the  ash  from  the  cartilage  of  a  shark,  and  such 
cartilage  can  scarcely  contain  quantities  of  chondromucoid  or  chon- 
droitic  acid  worth  mentioning.  The  cartilage  of  the  ray  {Raja 
batis  Lin.),  which  has  been  investigated  by  Lonnberg,  contains 
no  albumoid  and  only  a  little  chondromucoid,  but  a  large  propor- 
tion of  chondroitic  acid  and  collagen. 

The  Cornea.  The  corneal  tissue,  which  is  considered  by  many 
investigators  to  be  related  to  cartilage  in  a  chemical  sense,  contains 
traces  of  albumin  and  a  collagen  as  chief  constituent,  which  C.  Th. 
MoRNER  claims  contains  16.94^  N.  According  to  him  it  contains, 
a  mucoid  which  has  the  composition  C  50.16,  H  6.98,  N  12.8,  and 
S  2.05  per  cent.  On  boiling  with  dilute  acid  this  mucoid  yields 
a  reducing  substance. 

In  the  cornea  of  oxen  His  found  758.3  p.  m.  water,  203.8  p.  m. 
gelatin  forming  substance,  28.4  p.  m.  other  organic  substance, 
besides  8.1  p.  m.  soluble  and  1.1  p.  m.  insoluble  salts. 


238  PHTSIOLOQIGAL   CHEMISTRY. 


III.   Bone. 

The  bony  structure  proper^  when  free  from  other  formations 
occurring  in  bones,  such  as  marrow,  nerves,  and  blood-vessels,  con- 
sists of  cells  and  a  basic  substance. 

The  cells  have  not  been  closely  studied  in  regard  to  their  chemi- 
cal constitution.  On  boiling  with  water  they  yield  no  gelatine. 
They  contain  no  keratin,  which ,  is  not  usually  present  in  the  bony 
structure  (Heebeet  Smith),  but  they  may  contain  a  substance 
which  is  similar  to  elastin. 

The  basic  substance  of  the  bony  structure  contains  two  chief 
constituents,  namely,  an  organic  substance,  ossein,  and  the  so-called 
bone-earths  enclosed  in  or  combined  with  it.  If  bones  are  treated 
with  dilute  hydrochloric  acid  at  the  ordinary  temperature,  the  lime- 
salts  are  dissolved  and  the  ossein  remains  as  an  elastic  mass,  pre- 
serving the  shape  of  the  bone.  This  ossein  is  generally  considered 
identical  with  the  collagen  of  the  connective  tissue.  The  ossein  in 
the  bones  of  certain  aquatic  fowls  and  fishes  can  hardly  be  consid- 
ered identical  with  this  collagen  (Feemt). 

The  inorganic  constituents  of  the  bony  structure,  the  so-called 
bone-earths,  which  remain  after  the  complete  calcination  of  the 
organic  substance  as  a  white,  brittle  mass,  consist  chiefly  of  calcium 
and  phosphoric  acid,  but  also  include  carbon  dioxide  and,  in 
smaller  amounts,  magnesium,  chlorine,  and  fluorine.  Alkali  sul- 
phate and  iron,  which  are  found  in  the  bone-ash,  do  not  seem  to 
belong  exactly  to  the  bony  substance,  but  to  the  nutritive  fluids  or 
to  the  other  constituents  of  bones. 

The  opinions  of  investigators  differ  somewhat  as  to  the  manner 
in  which  the  mineral  bodies  of  the  bony  structure  are  combined 
with  each  other.  Chlorine  and  fluorine  are  present  in  the  same 
form  as  in  apatite  (CaFlg ,  SCasPgOg).  Proceeding  from  the  chlorine 
and  fluorine,  it  is  possible  that  the  other  mineral  bodies  form  the 
combination  3(Ca3P308)OaC03. 

Analyses  of  bone-earths  have  shown  that  the  mineral  constit- 
uents are  related  to  each  other  in  nearly  constant  proportions,  and 
this  applies  not  only  to  man  but  also  to  the  different  animals.     As 


TISSUES  OF  THE  CONNECTIVE  SUBSTANCE.  239 

example  of  the  constitution  of  boue-eartli  we  give  here  the  analyses 
of  Zalewsky.     The  figures  represent  parts  per  thousand. 

Mau.  Ox.  Tortoise.  Guinea-pig. 

Calcium  phosphate,  CaaP^Os 83S.9  860.9  859.8  873.8 

Magnesium  phosphate,  MgaPsOs 10.4  10.3  13.6  10.5 

Calcium  combined  with  COi.  Fl,  and  CI.     76.5  73.6  63.3  70.3 

Co, 57.3  63.0  53.7 

Chlorine 1.8  3.0  ....  1.3 

Fluorine  3.3  3.0  3.0 

Some  of  the  CO,  is  always  lost  on  calcining,  so  that  the  bone-ash  does  not 
contain  the  entire  CO,  of  the  bony  substance. 

The  quantity  of  organic  substance  in  the  bones,  calculated  from 
the  loss  of  weight  in  burning,  varies  somewhat  between  300  and 
520  p.  m.  This  variation  may  in  part  be  explained  by  the  difficulty 
in  obtaining  the  bony  substance  entirely  free  from  water,  and  partly 
by  the  very  variable  amount  of  blood-vessels,  nerves,  marrow,  and 
the  like  in  different  bones.  The  unequal  amounts  of  organic  sub- 
stance found  in  the  compact  and  in  the  spongy  parts  of  the  same 
bone,  as  well  as  in  bones  at  different  periods  of  development  in  the 
same  animal,  depend  probably  upon  the  varying  quantities  of 
these  above-mentioned  formations.  Dentin,  which  is  comparatively 
pure  bony  structure,  contains  only  260  to  280  p.  m.  organic  sub- 
stance, and  Hopfe-Seyler  therefore  thinks  it  probable  that  en- 
tirely pure  bony  substance  has  a  constant  composition  and  contains 
only  about  250  p.  m.  organic  substance.  The  question  whether 
these  substances  are  chemically  combined  with  the  bone-earths  or 
only  intimately  mixed  has  not  been  decided. 

The  nutritive  fluids  which  circulate  through  the  bones  have  not  been  iso- 
lated, and  we  only  know  that  they  contain  some  albumin  and  some  NaCl  and 
alkali  sulphate.  The  yellow  marrow  contains  chiefly  fat,  which  consists  of 
olein,  palmitiu,  and  stearin.  Albumin  has  been  found  especially  in  the  so- 
called  red  marrow  of  the  spongy  bones.  Besides  these  substances,  the  marrow 
contains  so-called  extractive  bodies,  such  as  lactic  acid,  hypoxanthiu,  and 
cholesteriu,  but  mostly  bodies  of  an  unknown  character. 

The  diverse  quantitative  composition  of  the  various  bones  of 
the  skeleton  depends  probably  on  the  varying  quantities  of  other 
formations,  such  as  marrow,  blood-vessels,  etc.,  they  contain.  The 
same  reason  explains,  to  all  appearances,  the  larger  quantity  of 
organic  substance  in  the  spongy  parts  of  the  bones  as  compared 
with  the  more  compact  parts.  Schrodt  has  made  comparative 
analyses  of  different  parts  of  the  skeleton  of  the  same  animal  (dog) 


240  PHYSIOLOGICAL  CHEMISTRY. 

and  has  found  an  essential  difference.  The  quantity  of  water  in 
the  fresh  bones  varies  between  138  and  443  p.  m.  The  bones  of 
the  extremities  and  the  skull  contain  138-222,  the  vertebrae  168- 
443,  and  the  ribs  324-356  p.  v^.  water.  The  quantity  of  fat  varies 
between  13  and  269  p.  m.  The  largest  amount  of  fat,  256-269 
p.  m.,  is  found  in  the  long  tubular  bones,  while  only  13-175  p.  m. 
fat  is  found  in  the  small  short  bones.  The  quantity  of  organic 
substance,  calculated  from  fresh  bones,  was  150-300  p.  m.,  and 
the  quantity  of  mineral  substances  290-563  p.  m.  Contrary  to 
the  general  supposition  the  greatest  amount  of  bone-earths  was  not 
found  in  the  femur,  but  in  the  three  first  cervical  vertebrae.  In 
geese  the  largest  amount  of  bone-earth  was  found  in  the  humerus 
(Hiller). 

We  do  not  possess  trustworthy  statements  in  regard  to  the  com- 
position of  bones  at  different  ages.  There  is  no  question,  however, 
that  the  mineral  constituents  increase  until  a  certain  age  is  reached, 
at  which  time  the  bones  attain  their  necessary  solidity.  On  the 
other  hand,  it  is  not  certainly  known  whether  this  increase  stops 
at  a  certain  point  or  whether,  as  was  formerly  thought,  it  con- 
tinues, even  if  slowly,  uninterrupted  from  childhood  to  old  age. 

The  composition  of  bones  of  animals  of  different  species  is  but  little 
known.  The  bones  of  birds  contain,  as  a  rule,  somewhat  more  water  than 
those  of  mammalia,  and  the  bones  of  fishes  contain  the  largest  quantity  of 
water.  The  bones  of  fishes  and  amphibians  contain  a  greater  amount  of 
organic  substance.  The  bones  of  pachydermata  and  cetacese  contain  a  large 
'proportion  of  calcium  carbonate  ;  those  of  granivorous  birds  always  contain 
silicic  acid.  The  bone-ash  of  amphibians  and  fishes  contains  sodium  sulphate. 
The  bones  of  fishes  seem  to  contain  more  soluble  salts  than  the  bones  of  other 
animals. 

A  great  many  tests  have  been  made  to  determine  the  exchange 
of  material  in  the  bones — for  instance,  with  food  rich  in  lime  and 
with  food  deficient  in  lime — but  the  results  have  always  been 
doubtful  or  contradictory.  The  attempts,  also,  to  substitute  other 
alkaline  earths  or  clay  for  the  lime  of  the  bones  have  given  contra- 
dictory results.  Krapp  found  that  the  bones  of  the  animals  under 
experimentation  were  tinged  with  red  after  a  few  days  or  weeks  ; 
but  these  tests  have  not  led  to  any  positive  conclusion  in  regard  to 
the  growth  or  exchange  of  material  in  the  bones. 

Under  pathological  conditions,  as  in  rachitis  and  softening  of 
the  bones,    an   ossein   has  been  found   which  does  not  give  any 


TISSUES  OF  THE  CONNECTIVE  SUBSTANCE.  241 

typical  gelatine  on  boiling  with  water.  Otherwise  the  pathological 
conditions  seem  to  affect  chiefly  their  quantitative  composition, 
and  especially  the  relationship  between  the  organic  and  the 
inorganic  substance.  In  exostosis  and  osteomalacosis  the  quantity 
of  organic  substance  is  generally  increased.  Attempts  have  been 
made  to  produce  rachitis  in  animals  by  the  use  of  food  deficient  in 
lime.  From  experiments  on  fully-developed  animals  contradictory 
results  have  been  obtained.  In  young,  undeveloped  animals  Erwin 
VoiT  produced,  by  lack  of  lime-salts,  a  change  similar  to  rachitis. 
In  full-grown  animals  the  bones  were  changed  after  a  long  time 
because  of  the  lack  of  lime-salts  in  the  food,  but  did  not  become 
soft,  only  thinner,  and  atrophied.  The  experiment  of  removing 
the  lime-salts  from  the  bones  by  the  addition  of  lactic  acid  to  the 
food  has  led  to  no  positive  results  (Heitzmann,  Heiss,  Baginskt). 
A  few  investigators  are  of  the  opinion  that  in  rachitis,  as  in 
osteomalacosis,  a  solution  of  the  lime-salts  by  means  of  lactic  acid 
takes  place.  This  was  suggested  by  the  fact  that  0.  Weber  and 
C.  Schmidt  found  lactic  acid  in  the  cyst-like,  altered  bony  sub- 
stance in  osteomalacia. 

Well-known  investigators  have  disputed  the  possibility  of  the 
lime-salts  being  washed  from  the  bones  in  osteomalacosis  by  means 
of  lactic  acid.  They  have  given  special  prominence  to  the  fact  that 
the  lime-salts  held  in  solution  by  the  lactic  acid  must  be  deposited 
on  neutralization  of  the  acid  by  the  alkaline  blood.  This  objection 
is  not  very  important,  as  the  alkaline  stream  of  blood  has  the  prop- 
erty to  a  high  degree  of  holding  earthy  phosphates  in  solution, 
which  can  be  easily  proved. 

In  rachitis  the  amount  of  organic  substance  has  been  found  to  vary  between 
664  and  811  p.  m.  The  quantity  of  iuorgauic  substance  was  189-336  p.  m. 
In  opposition  to  rachitis,  osteomalacosis  is  often  characterized  by  a  consider- 
able amount  of  fat  in  the  bones,  230-290  p.  m. ;  but  as  a  rule  the  composition 
varies  so  much  that  the  analyses  are  of  little  value. 

The  tooth-structure  is  nearly  related,  from  a  chemical  stand- 
point, to  the  bony  structure. 

Of  the  three  chief  constituents  of  the  teeth,  dentin,  enamel, 
and  cement,  the  last-mentioned,  the  cement,  is  to  be  considered  as 
true  bony  structure,  and  as  such  has  been  spoken  of  to  a  certain 
extent.     Dentin  has  the  same  composition  as  the  bony  structure, 


242  PHYSIOLOGICAL   CHEMISIRT. 

but  contains  somewhat  less  water.  The  organic  substance  yields 
gelatine  on  boiling;  but  the  dental  tubes  are  not  dissolved,  there- 
fore they  cannot  consist  of  collagen.  In  dentin  260-380  p.  m. 
organic  substance  has  been  found.  Enamel  is  an  epithelium  for 
mation  containing  a  large  proportion  of  lime-salts.  The  fact  that 
the  organic  substance  of  enamel  does  not  yield  any  gelatine  corre- 
sponds to  its  nature  and  origin.  Completely-developed  enamel 
contains  the  least  water,  the  greatest  quantity  of  mineral  sub- 
stances, and  is  the  hardest  of  all  the  tissues  of  the  body.  In  full- 
grown  animals  it  contains  hardly  any  water,  and  the  amount  of 
organic  substance  amounts  to  only  20-40  p.  m.  The  relative 
amounts  of  calcium  and  phosphoric  acid  are,  according  to  the 
analyses  of  Hoppe-Seyler,  about  the  same  as  in  bone-earths. 
According  to  the  determination  of  Berzelius,  the  enamel  may 
contain  40  p.  m.  calcium  fluoride. 


IV.  The  Fatty  Tissue. 

The  membranes  of  the  fat-cells  withstand  the  action  of  alcohol 
and  ether.  They  are  not  dissolved  by  acetic  acid  nor  by  dilute 
mineral  acids,  but  are  dissolved  by  artificial  gastric  juice.  They 
may  possibly  consist  of  a  substance  closely  related  to  elastin.  The 
contents  of  the  fat-cells  are  fluid  during  life,  but  solidify  after 
death  and  become  more  or  less  solid,  depending  upon  the  charac- 
ter of  the  fats.  Besides  fat,  the  fat-cells  contain  a  yellow  pigment 
which  in  emaciation  does  not  disappear  so  rapidly  as  the  fat;  and 
this  is  the  reason  that  the  subcutaneous  cellular  tissue  of  an  ema- 
ciated corpse  has  a  dark  orange-red  color.  The  cells  deficient  in 
or  nearly  free  from  fat,  which  remain  after  the  complete  disappear- 
ance of  the  latter,  seem  to  have  an  albuminous  protoplasm  rich  in 
water. 

The  less  water  the  fatty  tissue  contains,  the  richer  it  is  in  fat. 
ScHULTZE  and  Reixecke  found  in  1000  joarts : 

Water.  Membrane.  Fat. 

Fatty  tissue  of  oxen 99.6  11.6  888.8 

'<      "sheep  104.8  16.4  878.8 

"       "pigs 64.4  13.5  923.1 


TISSUES  OF  THE  CONNECTIVE  SUBSTANCE.  243 

The  fat  contained  in  the  fat-cells  consists  chiefly  of  triglycerides 
of  stearic,  palmitic,  and  oleic  acids.  Besides  these,  especially  in  the 
less  solid  kinds  of  fat,  there  are  glycerides  of  caproic,  valerianic, 
and  other  fatty  acids  which  have  not  been  so  closely  investigated. 
In  all  animal  fats  there  are  besides  these,  as  Hofmann  has  shown, 
free,  non-volatile  fatty  acids,  although  in  very  small  amounts. 
Fats  from  different  species  of  animals,  and  even  from  different 
parts  of  the  same  animal,  have  an  essentially  different  consistency, 
depending  upon  the  relative  amounts  of  the  different  fats.  In 
solid  fats — as  tallow — tristearin  and  tripalmitin  are  in  excess,  while 
the  less  solid  fats  are  characterized  by  a  greater  abundance  of 
palmitin  and  triolein.  This  last-mentioned  fat  is  found  in  greater 
quantities  proportionally  in  cold-blooded  animals,  and  this  accounts 
for  the  fat  of  these  animals  remaining  fluid  at  temperatures  at 
which  the  fat  of  warm-blooded  animals  solidifies.  Human  fat 
from  different  organs  and  tissues  contains,  in  round  numbers,  670- 
800  p.  m.  olein.  The  melting-point  of  different  fats  depends 
upon  the  composition  of  the  mixtures,  and  it  not  only  varies  for  fat 
from  different  tissues  of  the  same  animal,  but  also  for  the  fat  from 
the  same  tissues  in  various  kinds  of  animals. 

Fat  occurs  in  all  organs  and  tissues  of  the  animal  organism, 
though  the  quantity  may  be  so  variable  that  a  tabular  exhibit  of 
the  amount  of  fat  in  different  organs  is  of  little  interest.  The 
marrow  contains  the  largest  quantity  proportionally,  having  over 
960  p.  m.  The  three  most  important  deposits  of  fat  in  the  animal 
organism  are  the  intermuscular  connective  tissue,  the  fatty  tissue 
in  the  abdominal  cavity,  and  the  subcutaneous  connective  tissues. 

•The  average  composition  of  animal  fat  is  as  follows  :  C  76.5, 
H  12.0,  and  0  11.5  per  cent.  Neutral  fats  are  colorless  or  yel- 
lowish and,  when  perfectly  pure,  odorless  and  tasteless.  They  are 
lighter  than  water,  on  which  they  float  when  in  a  molten  condi- 
tion. They  are  insoluble  in  water,  dissolve  in  boiling  alcohol,  but 
separate  on  cooling, — often  in  crystals.  They  are  easily  soluble  in 
ether,  benzol,  and  chloroform.  The  fluid  neutral  fats  give  an 
emulsion  when  shaken  with  a  solution  of  gum  or  albumin.  With 
water  alone  they  give  an  emulsion  only  after  vigorous  and  pro- 
longed shaking,  bilt  the  emulsion  is  not  persistent.  The  presence 
of  some  soap  causes  a  very  fine  and  permanent  emulsion  to  form 


244  PH7SI0L0OIGAL   CHEMISTRY. 

easily.  Pat  produces  spots  on  paper  which  do  not  disappear ;  it 
is  not  volatile ;  it  boils  at  about  300°  0.  with  partial  decomposi- 
tion, and  burns  with  a  luminous  and  smoky  flame.  The  fatty  acids 
have  most  of  the  above-mentioned  properties  in  common  with  the 
neutral  fats,  but  differ  from  them  in  being  soluble  in  alcohol-ether,, 
in  having  an  acid  reaction,  and  by  not  giving  the  acrolein  test. 
The  neutral  fats  generate  a  strong  irritating  vapor  of  acrolein,  due 
to  the  decomposition  of  glycerine,  C3H5(OH)3  —  2H2O  =  CsH^O,. 
when  heated  alone,  or  more  easily  when  heated  with  potassium 
bisulphate  or  with  other  substances  removing  water. 

The  neutral  fats  may  be  split  by  the  addition  of  the  constitu- 
ents of  water  according  to  the  following  equation :  C3H5(OE)3  -f- 
3H2O  =  C3H5(OH)3  +  3H0R.  This  splitting  may  be  produced  by 
the  pancreatic  enzyme  or  by  superheated  steam.  We  most  fre- 
quently decompose  the  neutral  fats  by  boiling  them  with  caustic 
alkali  not  too  concentrated,  or,  still  better  (in  zoochemical  re- 
searches), with  an  alcoholic  potash  solution.  By  this  procedure, 
which  is  called  saponification,  the  alkali  salts  of  the  fatty  acids 
(soaps)  are  formed.  If  the  saponification  is  made  with  lead  oxide, 
then  lead-plaster,  lead-salts  of  the  fatty  acids,  is  produced. 

Stearin,  or  TRiSTEAKiif,  C3H5(Ci8H3502)3,  occurs  especially  in  the 
solid  varieties  of  tallow,  but  also  in  the  vegetable  fats. 

Stearic  acid,  OigHsgOg,  is  found  in  the  free  state  in  decomposed 
pus,  in  the  expectorations  in  gangrene  of  the  lungs,  and  in  cheesy 
tuberculous  masses.  It  occurs  as  lime-soap  in  excrements  and  adi- 
pocere,  and  in  this  last  product  also  as  an  ammonia  soap.  It  per- 
haps exists  as  sodium  soap  in  the  blood,  transudations,  and  pus. 

Stearin  is  the  hardest  and  most  insoluble  of  the  three  ordinary 
neutral  fats.  It  is  nearly  insoluble  in  cold  alcohol  and  soluble  with 
great  difficulty  in  cold  ether  (225  parts).  It  separates  from  warm 
alcohol  on  cooling  as  rectangular,  less  frequently  as  rhombical 
plates.  In  regard  to  the  melting-point,  which  may  be  changed  by 
alternately  warming  and  cooling,  opinions  are  somewhat  divergent; 
for  stearin  from  the  fatty  tissues  it  is  often  stated  as  63°  C. 

Stearic  acid  crystallizes  (on  cooling  from  boiling  alcohol)  in 
large,  shining,  long- rhombical  scales  or  plates.  It  is  less  soluble 
than  the  other  fatty  acids  and  melts  at  69.2°  0.  Its  barium  salt 
contains  19.49^  barium. 


TISSUES  OF  THE  CONNECTIVE  SUBSTANCE.  245 

Palmitin,  tripalmitin,  C3H5(Ci«H3i02)3.  Of  the  two  solid 
varieties  of  fats,  palmitin  is  the  one  which  occurs  in  predominant 
quantities  in  human  fat  (Langer).  Palmitin  is  jjresent  in  all 
animal  fats  and  in  several  kinds  of  vegetable  fats.  A  mixture  of 
sterin  and  palmitin  was  formerly  called  margarin.' 

Palmitic  acid,  C16H32O2.  As  to  occurrence  about  the  same  remarks 
apply  as  to  stearic  acid.  The  mixture  of  these  two  acids  has  been 
called  margaric  acid,  and  this  mixture  occurs — often  as  very  long, 
thin,  crystalline  plates — in  old  pus,  in  expectorations  from  gang- 
rene of  the  lungs,  etc. 

Palmitin  crystallizes,  on  cooling  from  a  warm  saturated  solution 
in  ether  or  alcohol,  into  starry  rosettes  of  fine  needles.  The  mix- 
ture of  palmitin  and  stearin,  called  margarin,  crystallizes,  on  cool- 
ing from  a  solution,  as  balls  or  round  masses  which  consist  of  short 
or  long,  thin  plates  or  needles  which  often  appear  like  blades  of 
grass.  Palmitin,  like  stearin,  has  a  variable  melting  and  solidify- 
ing point,  depending  upon  the  way  it  has  been  previously  treated. 
The  melting-point  is  often  given  as+  62°  and  the  solidifying-point 
as  +  45°  C. 

Palmitic  acid  crystallizes  from  an  alcoholic  solution  in  tufts  of 
fine  needles.  It  melts  at  +  62°  C;  still  the  admixture  with  stearic 
acid,  as  Heintz  has  shown,  essentially  changes  the  melting  and 
solidifying  points  according  to  the  relative  amounts  of  the  two  acids. 
Palmitic  is  somewhat  more  soluble  in  cold  alcohol  than  stearic  acid ; 
but  they  have  about  the  same  solubility  in  boiling  alcohol,  ether, 
chloroform,  and  benzol. 

Olein,  triolein,  C3H5(Ci8H3302)s  ,  is  present  in  all  animal  fats 
and  in  greater  quantities  in  plant  fats.  It  is  a  solvent  for  stearin 
and  palmitin.  Oleic  acid,  elaic  acid,  CigHs^Og,  occurs  probably 
as  soaps  in  the  intestinal  canal  during  digestion  and  in  the  chyle. 

Olein  is,  at  ordinary  temperatures,  a  nearly  colorless  oil  of  a 
specific  gravity  of  0.914,  without  odor  or  marked  taste.  It  solidifies 
in  crystalline  needles  at  —  5°  C.  It  becomes  rancid  quickly  if 
exposed  to  the  air.  It  dissolves  with  difiiculty  in  cold  alcohol,  but 
more  easily  in  warm  alcohol  or  in  ether.  It  is  converted  into  its 
isomer,  elaidin,  by  nitrous  acid. 

^  This  mixture  must  not  be  confounded  with  the  synthetically-prepared 
neutral  fat  called  tnmargiirin. 


246  PET8I0L0QICAL  CEEMISTBT. 

Oleic  acid  forms  at  ordinary  temperature  a  colorless,  tasteless, 
and  odorless  oily  liquid  which  crystallizes  at  about  +  4°  C.  On 
being  heated  it  yields,  besides  volatile  fatty  acids,  sebacic  acid, 
CioHigOi ,  which  crystallizes  in  shining  plates  and  melts  at  -|-  127°  C. 
Oleic  acid  is  converted  by  nitrous  acid  into  its  isomer,  elaidic  acid, 
which  is  a  solid,  melting  at  +45°  C.  Oleic  acid  is  insoluble  in 
water  but  dissolves  in  alcohol,  ether,  and  chloroform.  With  con- 
centrated sulphuric  acid  and  some  cane-sugar  it  gives  a  beautiful 
red  or  reddish-violet  liquid  whose  color  is  similar  to  that  produced 
in  Petten^kofer's  test  for  bile-acids. 

If  the  watery  solution  of  the  alkali  combinations  of  oleic  acid  is 
precipitated  with  lead  acetate,  a  white,  tough,  sticky  mass  of  oleate 
of  lead  is  obtained  which  is  not  soluble  in  water  and  only  slightly 
in  alcohol,  but  is  soluble  in  ether  {differing  from  the  lead-salts  of 
the  other  two  fatty  acids). 

An  acid  related  to  oleic  acid,  doglingic  acid,  which  is  solid  at  0°  C,  liquid 
at  -\-  16°,   and  soluble  in  alcohol,  is  found  in  the  blubber  of  the  bal^na 

ROSTRATA. 

To  detect  the  presence  of  fat  in  an  animal  fluid  or  tissue  the 
fat  must  first  be  extracted  with  ether.  After  the  evaporation  of  the 
ether  the  residue  is  tested  for  fat  and  the  acrolein  test  must  not  be 
neglected.  If  this  test  gives  positive  results,  then  neutral  fats  are 
present;  if  the  results  are  negative,  then  only  fatty  acids  are  present. 
If  the  above  residue  after  evaporation  gives  the  acrolein  test,  then  a 
small  portion  is  dissolved  in  alcohol-ether  free  from  acid  and  which 
has  been  colored  bluish  violet  by  tincture  of  alkanet.  If  the  color 
becomes  red,  a  mixture  of  neutral  fat  and  fatty  acids  is  present.  In 
this  case  the  fat  is  treated  in  the  warmth  with  a  soda  solution  and 
evaporated  on  the  water-bath,  constantly  stirring  until  all  the  water 
is  removed  The  fatty  acids  are  hereby  combined  with  the  alkali 
as  soaps,  while  the  neutral  fats  are  not  saponified  under  these  con- 
ditions. If  this  mixture  of  soaps  and  neutral  fats  is  treated  with 
water  and  then  shaken  with  pure  ether,  the  neutral  fats  are  dis- 
solved, while  the  soaps  remain  in  the  watery  solution.  The  fatty 
acids  may  be  separated  from  this  solution  by  the  addition  of  a 
mineral  acid  which  sets  the  acid  free. 

The  neutral  fats  separated  from  the  soaps  by  means  of  ether  are 
contaminated  with  some  cholesterin,  which  must  be  separated  in 
quantitative  determinations  by  saponification  with  alcoholic  caustic 
potash. 

The  cholesterin  is  not  attacked  by  the  caustic  alkali  while  the 
neutral  fats  are  saponified.     After  the  evaporation  of  the  alcohol 


TISSUES  OF  THE  CONNECTIVE  SUBSTANCE.  247 

the  residue  is  dissolved  in  water  and  shaken  with  ether,  which  dis- 
solves the  cholesterin.  The  fatty  acids  are  separated  from  the 
watery  solution  of  the  soaps  by  the  addition  of  a  mineral  acid.  If 
a  mixture  of  soaps,  neutral  fats,  and  fatty  acids  is  originally  present, 
it  is  treated  first  with  water,  then  agitated  with  ether  free  from 
alcohol,  which  dissolves  the  fat  and  fatty  acids,  while  the  soaps 
remain  in  the  solution,  with  the  exception  of  a  very  small  amount 
which  is  dissolved  by  the  ether. 

To  detect  and  to  separate  the  different  varieties  of  neutral  fats 
from  each  other  it  is  best  first  to  saponify  them  with  alcoholic 
potash.  After  the  evaporation  of  the  alcohol  they  are  dissolved  in 
water  and  precipitated  with  sugar  of  lead.  The  oleate  of  lead  is 
then  separated  from  the  other  two  lead-salts  by  repeated  extraction 
with  ether.  The  residue  insoluble  in  ether  is  decomposed  on  the 
water-bath  with  an  excess  of  soda  solution,  evaporated  to  dryness, 
finely  pulverized,  and  extracted  with  boiling  alcohol.  The  alcoholic 
solution  is  then  fractionally  precipitated  by  barium  acetate  or 
barium  chloride.  In  one  fraction  the  amount  of  barium  is  deter- 
mined, and  in  the  other  the  melting-point  of  the  fatty  acid  set  free 
by  a  mineral  acid.  The  fatty  acids  occurring  originally  in  the  ani- 
mal tissues  or  fluids  as  free  acids  or  as  soaps  are  converted  into 
barium  salts  and  investigated  as  above. 

The  derivation  of  the  fats  in  the  organism  may  occur  in  various 
ways.  The  fat  of  the  animal  body  may  consist  partly  of  absorbed 
fat  of  the  food  deposited  in  the  tissues  and  partly  of  fat  formed  in 
the  organism  from  other  bodies,  such  as  albuminous  bodies  or 
carbohydrates. 

That  the  fat  of  the  food  which  is  absorbed  in  the  intestinal 
canal  may  be  retained  by  the  tissues  has  been  shown  in  several 
ways.  Lebedeff  and  Munk  have  fed  dogs  with  various  fats,  such 
as  linseed-oil,  mutton-tallow,  and  rape-seed-oil,  and  have  afterwards 
found  the  administered  fat  in  the  tissues.  Hofmanx  starved  dogs 
until  they  appeared  to  have  lost  their  fat,  and  then  fed  them  upon 
large  quantities  of  fat  and  only  little  proteids.  When  the  animals 
were  killed  he  found  so  large  a  quantity  of  fat  that  it  could  not 
have  been  formed  from  the  administered  proteids  alone,  but  the 
greatest  part  must  have  been  derived  from  the  fat  of  the  food. 
Pettenkofer  and  Voit  arrived  at  similar  results  in  regard  to  the 
behavior  of  the  absorbed  fats  in  the  organism,  though  their  experi- 
ments were  of  another  kind.  Munk  has  found  that  on  feeding 
with  free  fatty  acids,  these  are  deposited  in  the  tissues,  not,  how- 


248  PHYSIOLOGICAL   CHEMISTRY. 

ever,  as  such;  but  they  are  transformed  by  synthesis  with  glycerin 
into  neutral  fats  on  their  passage  from  the  intestines  to  the 
thoracic  duct.  According  to  Ewald,  such  a  synthesis  may  be  pro- 
duced by  the  surviving  mucous  membrane  of  the  intestine. 

Albuminous  bodies  and  carbohydrates  may  be  considered  as  the 
mother-substance  of  the  fats  formed  in  the  organism. 

The  formation  of  the  so-called  coepse-wax,  adipocere,  into 
which  parts  of  the  corpse  rich  in  proteids  are  sometimes  converted, 
and  which  consists  of  abundant  quantities  of  fatty  acids,  ammonia, 
and  lime-soaps,  is  often  given  as  a  proof  of  the  formation  of  fats 
from  proteids.  The  provableness  of  this  observation  has,  however, 
been  disputed,  and  many  other  explanations  of  the  formation  of 
this  substance  have  been  offered.  According  to  the  recent  experi- 
ments of  Kratter  and  K.  B.  Lehmann",  it  seems  as  if  it  were 
possible  by  experimental  means  to  convert  animal  tissue  rich  in 
proteids  (muscles)  into  adipocere  by  the  continuous  action  of  water. 
That  the  formation  of  fatty  acids  in  this  case  actually  takes  place 
at  the  expense  of  the  proteids  may  be  inferred  from  the  investiga- 
tions of  Lehmank. 

Another  proof  of  the  formation  of  fat  from  proteids,  taken 
from  pathological  chemistry,  is  fatty  degeneration.  On  this  point 
also  all  investigators  are  not  united;  but  the  investigations  of 
Bauer  seem  to  show  that  at  least  in  acute  poisoning  by  phosphorus 
the  fatty  degeneration  actually  consists  of  a  formation  of  fat  from 
proteids. 

As  a  more  direct  proof  of  fat-formation  from  proteids  the  inves- 
tigations of  Pettenkofer  and  Voit  are  often  quoted.  These 
investigators  fed  dogs  with  large  quantities  of  meat  containing  the 
least  possible  proportion  of  fat,  and  found  all  of  the  nitrogen  in 
the  excreta  but  only  a  part  of  the  carbon.  As  an  explanation  of 
these  conditions  it  has  been  assumed  that  the  proteid  of  the 
organism  splits  into  a  nitrogenized  and  a  non-nitrogenized  part, 
the  former  changing  into  the  nitrogenized  final  product,  urea,  the 
other,  on  the  contrary,  being  retained  in  the  organism  as  fat  (Pet- 
tenkofer  and  Voit). 

Another  more  direct  proof  of  a  fat  formation  from  proteid  has 
been  given  by  Hofmann.  He  experimented  with  fly-maggots.  A 
number  of  these  were  killed  and  the  quantity  of  fat  determined. 


TISSUES  OF  THE  CONNECTIVE  SUBSTANCE.  249 

The  remainder  were  allowed  to  develop  iu  blood  whose  proportion 
of  fat  had  been  previously  determined,  and  after  a  certain  time 
they  were  killed  and  analyzed.  He  found  in  them  from  7  to  19 
times  as  much  fat  as  the  maggots  first  analyzed  and  the  blood 
together  contained. 

While,  then,  in  view  of  this  experiment,  the  question  of  the 
formation  of  fat  from  proteids  can  hardly  be  disputed,  we  do  not 
yet  know  the  maximum  amount  of  fat  formed  from  the  proteids 
nor  the  chemical  processes  concerned  in  its  formation.  Drechsel, 
mindful  of  the  products  which  are  formed  by  the  decomposition  of 
albumin  with  barium  hydrate,  has  called  attention  to  the  fact  that 
the  albumin  molecule  probably  originally  contains  no  radical  with 
more  than  six  or  nine  carbon  atoms.  If  fat  is  formed  from  albu- 
min in  the  animal  body,  then,  according  to  Drechsel,  such  forma- 
tion is  not  a  splitting  off  from  the  albumin,  but  rather  a  synthesis 
from  primarily-formed  splitting  products  of  albumin  which  are 
deficient  in  carbon. 

The  theory  of  the  formation  q  fat  from  carbohydrates  in  the 
animal  body  was  first  adopted  by  Liebig.  This  was  combated  for 
some  time,  however,  and  until  lately  it  was  the  general  opinion  that  a 
direct  formation  of  fat  from  carbohydrates  had  not  been  proved, 
and  also  that  it  was  improbable.  The  undoubtedly  great  influence 
which  Liebig  has  shown  the  carbohydrates  to  exert  on  the  forma- 
tion of  fat  has  been  explained  by  C.  v.  VoiT  upon  the  assumption 
that  these  carbohydrates  are  consumed  instead  of  the  fat  absorbed 
or  formed  from  the  albumins,  and  therefore  have  an  action  tending 
to  economize  the  fat.  By  means  of  a  series  of  nutrition  tests 
with  foods  especially  rich  in  carbohydrates,  Lawes  and  Gilbert, 
SoxHLET,  TscHERWiiirsKY,  Meissl  and  Stromer  (on  pigs),  B. 
Schultze,  Chaniewski,  E.  Voit  and  C.  Lehmakn"  (on  geese),  J. 
MuNK  and  M.  Eubner  (on  dogs)  apparently  prove  that  a  direct 
formation  of  fat  from  carbohydrates  does  actually  occui*.  The 
processes  by  which  this  formation  takes  place  are  still  unknown. 
As  the  carbohydrates  do  not  contain  as  complicated  a  molecule  as 
the  fats,  the  formation  of  fat  from  carbohydrates  must  consist  of  a 
synthesis,  in  which,  the  group  CHOH  is  converted  into  CHg ,  a 
reduction  must  also  take  place. 

"When  food  contains  an  excess  of  fat,  the  superfluous  amount  is 


250  PHTSIOLOQICAL   CHEMI8TRT. 

stored  up  in  the  fatty  tissue,  and  on  partaking  of  food  deficient  in 
fat  this  accumulation  is  quickly  exhausted.  There  is  perhaps  no  one 
of  the  various  tissues  tliat  decreases  so  much  in  starvation  as  the 
fatty  tissue.  The  organism,  then,  possesses  in  this  tissue  a  depot 
where  there  is  stored  during  proper  alimentation  a  substance  of 
great  importance  in  the  development  of  heat  and  vital  force,  which 
substance,  on  insufficient  nutrition,  is  given  off  as  may  be  needed. 
The  fatty  tissues,  on  account  of  their  low  conducting  power, 
become  of  great  importance  in  regulating  the  loss  of  heat  from  the 
body.  They  also  serve  to  fill  cavities,  and  as  a  protection  and  sup- 
port to  certain  internal  organs. 

Appendix  to  the  Fatty  Tissue. 

Spermaceti.  In  the  living  spermaceti  or  -white  whale  there  is  found  in  a 
large  cavity  in  the  skull  an  oily  liquid  called  spermaceti,  which  on  cooling 
after  death  separates  into  a  solid  crystalline  part,  ordinarily  called  spermaceti, 
and  into  a  liquid,  spermaceti-oil.  This  last  is  separated  by  pressure.  Sper- 
maceti is  also  found  in  other  whales  and  in  certain  species  of  dolphin. 

The  puritied,  solid  spermaceti,  which  is  called  cetin,  is  a  mixture  of  esters 
of  fatty  acids.  The  chief  constituent  is  the  cetyl  palmitic  ester  mixed  with 
small  quantities  of  compound  ethers  of  lauric,  myrisitic,  and  stearic  acids  with 
radicals    of  the  alcohols,  lethal,    CiaHus.OH,    methal,    C14H29.OH,    and 

STETHAL,  C18H37.OH. 

Cetin  is  a  snow-white  mass  shining  like  mother-of-pearl,  crystallizing  in 
plates,  brittle,  fatty  to  the  touch,  and  which  has  a  varying  melting-point 
of  -I-  30°  to  50°  C,  depending  upon  its  purity.  Cetin  is  insoluble  in  water,  but 
dissolves  easily  in  cold  ether  or  volatile  and  fatty  oils.  It  dissolves  in  boiling 
'alcohol,  but  crystallizes  on  cooling.  It  is  saponified  with  difficulty  by  a  solu- 
tion of  caustic  potash  in  water,  but  with  an  alcoholic  solution  it  saponifies 
readily  and  the  above-mentioned  alcohols  are  set  free. 

Ethal,  or  cetyl  alcohol,  CsHsa.  OH,  which  also  occurs  in  the  coccygeal 
gland  of'  ducks  and  geese  (De  Jqnge)  and  in  smaller  quantities  in  beeswax, 
forms  white  transparent,  odorless,  and  tasteless  crystals  which  are  insoluble 
in  water  but' dissolve  easily  in  alcohol  and  ether.     Ethal  melts  at  49.5°  C. 

Spermaceti- OIL  yields  on  saponification  valerianic  acid,  small  amounts  of 
solid  fatty  acids,  and  physetoleic  acid.  This  acid  forms  colorless  and  odor- 
less,  needle-shaped  crystals  which  easily  dissolve  in  alcohol  and  ether  and 

^Beeswax  may  be  treated  here  as  concluding  the  subject  of  fats.  It  con- 
tains three  chief  constituents.  1.  Cerotic  acid,  C27HB4O2  ,  which  occurs  as 
cetvl  ether  in  Chinese  wax  and  as  free  acid  in  ordinary  wax.  It  dissolves  in 
boiling  alcohol  and  separates  as  crystals  on  cooling.  The  cooled  alcoholic 
extract  of  wax  contains  (2)  cerolein,  which  is  probably  a  mixture  of  several 
bodies  and  (3)  myrisin,  which  forms  the  chief  constituent  of  that  part  of 
wax  which  is  insoluble  in  warm  or  cold  alcohol.  Myrisin  consists  chiefly  of 
palmitic-acid  ether  of  melissyl  (myricyl)  alcohol,  CaoHej.OH.  This  alcohol 
IS  a  silky,  shining,  crystalline  body  melting  at  +  85°  C. 


CHAPTER  IX. 

MUSCLE.  ^ 

Striated  Muscles. 

In  the  study  of  the  muscles  the  chief  problem  for  physiological 
chemistry  is  to  isolate  their  different  morphological  elements  and 
to  investigate  each  element  separately.  By  reason  of  the  compli- 
cated structure  of  the  muscles  this  has  been  thus  far  almost  impos- 
sible, and  we  must  be  satisfied  at  the  present  time  with  the  investi- 
gation of  the  chemical  composition  of  the  muscular  fibres  and  with 
a  few  micro-chemical  reactions. 

Each  muscle-tube  or  muscle-fibre  consists  of  a  sheath,  the 
SARCOLEMMA,  which  apparently  is  composed  of  a  substance  similar 
to  elastin,  and  the  contents  containing  a  large  proportion  of 
ALBUMINS.  This  last-mentioned  substance,  which  in  life  is  possessed 
of  contractile  force,  has  in  the  inactive  muscle  an  alkaline  reaction, 
or,  more  correctly  speaking,  an  amphoteric  reaction  with  a  predomi- 
nating action  on  red  litmus-paper.  This  reaction  depends  on  a 
mixture  of  mono-  and  di-potassium  phosphate  with  a  preponderance 
of  diphosphate.  The  dead  muscle  has,  on  the  contrary,  an  acid 
reaction  depending  on  the  presence  of  potassium  monophosphate 
and  free  lactic  acid. 

If  we  disregard  the  disputed  statements  relative  to  the  finer 
structure  of  the  muscles,  we  can  differentiate  in  the  striated  muscles 
between  the  two  chief  components,  the  doubly  refracting — aniso- 
tropous — and  the  singly  refracting — isotropons — substance.  If  the 
muscular  fibres  are  treated  with  reagents  which  dissolve  albumins, 
such  as  dilute  hydrochloric  acid,  soda  solution,  or  gastric  juice, 
they  swell  greatly  and  break  up  into  ''Bowman's  disks."  By  the 
action  of  alcohol,  chromic  acid,  boiling  water,  or  in  general  such 

251 


252  PHYSIOLOGICAL  CHEMISTRY. 

reagents  as  cause  a  shrinking,  the  fibres  split  longitudinally  into 
fibrils ;  and  this  behavior  shows  that  several  chemically  different 
substances  of  various  solubilities  enter  into  the  construction  of  the 
muscular  fibres. 

The  albuminous  body,  myosin,  is  generally  considered  as  the 
principal  constituent  of  the  diagonal  disks,  consisting  of  a  doubly- 
refracting  substance,  while  the  chief  mass  of  the  remaining  albumin- 
ous bodies  found  in  the  muscles,  also  most  of  the  extractive  matter, 
is  contained  in  the  isotropous  substance.  According  to  the  obser- 
vations of  Danilewskt,  myosin  may  be  completely  extracted  from 
the  muscle  without  changing  its  structure,  by  the  use  of  a  5^  solu- 
tion of  ammonium  chloride.  This  is  contrary  to  the  above  state- 
ments. Danilewsky  claims  that  in  the  structure  of  the  muscles 
another  substance  enters,  similar  to  albumin,  which  has  not  been 
closely  studied  and  which  does  not  dissolve  in  ammonium  chloride 
solution,  but  only  expands.  Albuminous  bodies  constitute  an 
important  part  of  the  muscular  structure,  of  which  it  forms  the 
chief  mass  of  its  solids. 

Albuminous  Bodies  of  the  Muscles. 

Like  the  blood  which  contains  a  fluid,  the  blood-plasma,  which 
spontaneously  coagulates,  separating  fibrin  and  yielding  blood-serum, 
so  also  the  living  muscle  contains,  as  first  shown  by  KiJHifE,  a 
spontaneously  coagulating  liquid,  the  muscle-plasma,  which  coagu- 
lates quickly,  separating  an  albuminous  body,  myosin,  and 
yielding  also  a  serum.  That  liquid  which  is  obtained  by  pressing 
the  living  muscle  is  called  muscle-plasma,  while  that  obtained  from 
the  dead  muscle  is  called  muscle-serum.  These  two  fluids  also  con- 
tain different  albuminous  bodies. 

The  muscle-plasma  was  first  prepared  by  KiiKNE  from  frog- 
muscles,  and  lately  Hallibuetok  has  prepared  it  according  to  the 
same  method  from  the  muscles  of  warm-blooded  animals,  especially 
rabbits.  The  principle  of  this  method  is  as  follows :  The  blood  is 
removed  from  the  muscles  immediately  after  the  death  of  the  animal 
by  passing  through  them  a  strongly-cooled  common-salt  solution  of 
5  to  6  p.  m.  Then  the  quickly-cut  muscles  are  immediately 
thoroughly  frozen  so  that  they  can  be  ground  in  this  state  to  a  fine 
mass — "  muscle-snow."  This  pulp  is  strongly  pressed  in  the  cold,  and 


MUSCLE.  253 

the  liquid  which  drips  off,  the  muscle-plasma,  is  faintly  yellowish  in 
color,  alkaline,  and  spontaneously  but  slowly  coagulates  at  a  little 
above  0°  C,  but  very  quickly  at  the  temperature  of  the  body.  In 
the  muscle-plasma  of  the  frog  the  reaction  does  not  change  imme- 
diately with  the  coagulation,  but  the  alkaline  reaction  is  gradually 
changed  into  an  acid  one.  The  liquid  which  is  pressed  from  tne 
clot,  the  muscle-serum,  is  always  acid.  Tlie  albuminous  body  which 
forms  the  clot  has  been  called  myosin.  Besides  this,  another 
albuminous  body,  musculin  or  paramyosin  (Halliburton),  is 
found  in  the  clot. 

Myosin  was  first  discovered  by  Kuhne,  and  constitutes  the 
principal  mass  of  the  albuminous  bodies  of  the  dead  muscle,  and 
according  to  a  few  investigators  it  forms  the  greatest  part  of  the 
contractile  protoplasma.  The  statements  as  to  the  occurrence  of 
myosin  in  other  organs  besides  the  muscles  require  further  proof. 
The  amount  of  myosin  in  the  muscles  of  different  animals  varies, 
according  to  Da.nilewsky,  between  30-110  p.  m. 

Myosin  is  a  globulin  whose  elementary  composition,  according 
to  Chittenden  and  Cummins,  is,  on  an  average,  the  following  : 
C  52.83,  H  7.11,  N16.17,  S  1.27,  022.03  per  cent.  If  the 
myosin  separates  as  fibres,  or  if  a  myosin  solution  with  a  minimum 
quantity  of  alkali  is  allowed  to  evaporate  on  a  microscope-slide  to  a 
gelatinous  mass,  doubly-refracting  myosin  may  be  obtained.  Myosin 
has  the  general  properties  of  the  globulins.  It  is  completely  pre- 
cipitated by  saturating  with  NaCl,  also  by  MgSOi,  in  a  solution 
containing  94^  of  the  salt  with  its  water  of  crystallization  (Halli- 
burton). Like  fibrinogen  it  coagulates  at  +  56°  C.  in  a  solution 
containing  common  salt,  but  differs  from  it  since  under  no  circum- 
stances can  it  be  converted  into  fibrin.  The  coagulation  tempera- 
ture, according  to  Chittenden  and  Cummins,  not  only  varies  for 
myosin  of  different  origin,  but  also  for  the  same  myosin  in  different 
salt  solutions. 

Myosin  may  be  prepared  in  the  following  way,  as  suggested  by 
Halliburton.  The  muscle  is  first  extracted  by  a  bfc  magnesium 
sulphate  solution.  The  filtered  extract  is  then  treated  with  mag- 
nesium sulphate  in  substance  until  100  cc.  of  the  liquid  contains 
about  50  grms.  of  the  salt.  The  so-called  paramyosin  or  musculin 
separates.       The   filtered  liquid  is  then  treated  with  magnesium 


254  PET8I0L0OIGAL   CEEMISTRT. 

sulphate  until  each  100  cc.  of  the  liquid,  holds  94  grms.  of  the  salt 
in  solution.  The  myosin  which  now  separates  is  filtered,  dissolved 
in  water  by  aid  of  the  retained  salt,  precipitated  by  diluting  with 
water,  and,  when  necessary,  purified  by  redissolving  in  dilute-salt 
solution  and  precipitating  with  water. 

The  older  and  perhaps  the  usual  method  of  preparation  consists, 
according  to  Danilbwskt,  in  extracting  the  muscle  with  a  5-10^ 
ammonium-chloride  solution,  precipitating  the  myosin  from  the 
filtrate  by  strongly  dilating  with  water,  redissolving  the  precipitate 
in  ammonium-chloride  solution,  and  the  myosin  obtained  from  this 
solution  is  either  reprecipitated  by  diluting  with  water  or  by  remov- 
ing the  salt  by  dialysis. 

As  the  coagulation  of  the  blood-plasma  is  considered  by  most 
investigators  as  an  enzymotic  process,  so  certain  observations  seem 
to  show  that  the  coagulation  of  the  muscle-plasma  is  an  analogous 
process.  From  muscles  which  had  been  kept  for  a  long  time  in 
alcohol  Halliburton  obtained,  by  extracting  the  mass  with 
water,  a  soluble  substance  contaminated  with  albumose  which, 
although  not  identical  with  fibrin  ferment,  had  the  property 
of  accelerating  the  coagulation  of  the  muscle-plasma.  This  sub- 
stance was  called  by  him  "  myosin-ferment." 

As  in  the  blood-plasma  we  have  a  mother-substance  of  fibrin, 
fibrinogen,  so  also  it  is  considered  that  in  the  muscle-plasma  we 
have  a  mother-substance  of  myosin,  myosinogen.  This  body  has  not 
thus  far  been  isolated  with  certainty.  HALLiBURTOiir  found  that 
a  solution  of  purified  myosin  in  dilute-salt  solution  (5^  MgSOi), 
and  suificiently  diluted  with  water,  coagulates  after  a  certain 
time,  and  at  the  same  time  becomes  acid  and  a  typical  myosin-clot 
separates.  This  coagulation,  which  is  accelerated  by  warming  or 
by  the  addition  of  myosin-ferment,  is,  according  to  Halliburton, 
a  process  analogous  to  the  coagulation  of  the  muscle-plasma.  Ac- 
cording to  this  same  investigator,  myosin  when  dissolved  in  water 
by  the  aid  of  a  neutral  salt  is  reconverted  into  myosinogen,  while 
after  diluting  with  water  myosin  is  again  produced  from  the 
myosinogen.  These  observations  may,  however,  be  explained  in 
other  ways.  In  these  cases  the  separation  of  the  myosin  is  evi- 
dently closely  connected  with  the  liquid  becoming  acid,  while  the 
separation  of  myosin  from  the  muscle-plasma,  at  least  from  the 
muscle-plasma  of  the  frog,  is  independent  of  this  acidity,  for  it  may 


MUSCLE.  255 

take  place  before  the  liquid  becomes  acid.  The  mother-substance 
of  myosin  and  the  chemical  processes  of  the  myosin  coagulation  are 
questions  which  must  not  be  considered  as  settled. 

Musculin,  called  paramyosinogen  by  Halliburton,  is  a  glob- 
ulin which  is  characterized  by  its  low  coagulation  temperature, 
about  -f  47°  C,  which  may  vary  in  different  species  of  animals 
(-}-  45°  in  frogs,  +  51°  C.  in  birds).  It  is  more  easily  dissolved 
than  myosin  by  NaCl  or  MgSOi  (salt  containing  50^  water  of 
crystallization).  Musculin  is  separated  simultaneously  with  myosin 
in  the  coagulation  of  the  muscle-plasma,  and  it  is  therefore  found 
in  the  clot.  A  solution  which  contains  musculin  and  no  myosin 
does  not  coagulate  on  the  addition  of  the  myosin  ferment  (Halli- 
burton). If  the  dead  muscle  is  extracted  with  water,  the  mus- 
culin passes  in  part  into  solution.  The  musculin  may  be  isolated 
by  fractional  precipitation  with  magnesium  sulphate  (50  grms.  to 
each  100  cc.  liquid),  and  may  be  identified  by  its  low  coagulation 
temperature. 

Myoglobulin.  After  the  separation  of  the  musculin  and  the 
myosin  from  the  salt  extract  of  the  muscle  by  means  of  MgSOi  the 
myoglobulin  may  be  precipitated  by  saturating  the  filtrate  with  the 
salt.  It  is  similar  to  serum  globulin,  but  coagulates  at  -f-  63°  C. 
(Halliburton).  Myoalbumin,  or  muscle-albumin,  seems  to  be 
identical  with  serum-albumin  (serum-albumin  a,  according  to  Hal- 
liburton), and  is  prepared  according  to  the  same  method.  Myo- 
alhiimose  (a  deuteroalbumose)  is  found  in  small  quantities  in  the 
muscles,  and  may  be  obtained  by  extracting  with  water  the  finely- 
divided  mass  of  muscle  which  has  previously  been  coagulated  by 
keeping  in  alcohol  for  a  long  time  (Halliburton). 

After  the  complete  removal  from  the  muscle  of  all  albuminous 
bodies  which  are  soluble  in  water  and  ammonium  chloride,  Dani- 
levtsky  claims  that  an  insoluble  albuminons  body  remains  which 
only  swells  in  ammonium-chloride  solution  and  which  forms  with 
the  other  insoluble  constituents  of  the  muscular  fibre  the  "  muscle- 
stroma."  According  to  Danilewsky,  the  amount  of  such  stroma 
substance  is  connected  with  the  muscle  activity.  He  maintains 
that  the  muscles  contain  a  greater  amount  of  this  substance,  com- 
pared with  the  myosin  present,  when  the  muscles  are  quickly  con- 
tracted and  relaxed. 


256  PHYSIOLOGICAL  CHEMISTRY. 

Muscle-syntonin,  which  may  be  obtained  by  extracting  the 
muscles  with  hydrochloric  acid  of  1  p.  m.,  and  which,  according  to 
K.  MoRNER,  is  less  soluble  and  has  a  greater  aptitude  to  precipitate 
than  other  acid  albumins,  seems  not  to  occur  pre-existent  in  the 
muscles. 

Muscle-coloring  Matters.  There  is  no  question  that  the  red 
color  of  the  muscles  even  when  completely  freed  from  blood  de- 
pends in  part  on  hasmoglobin,  though  it  is  contested  by  many. 
MacMunn  claims  that  the  muscles  contain  also  another  coloring 
substance  which  is  nearly  related  to  the  blood-coloring  matters  and 
whose  spectrum  is  very  similar  to  that  of  hsemochromogen.  This 
coloring  matter  has  been  called  myohcBinatin.  According  to  Levy 
and  Hoppe-Setler,  this  myohsematin  is  nothing  but  hsemochromo- 
gen,  which  is  produced  from  oxy haemoglobin  by  decomposition 
and  reduction.  Nevertheless  MAcMuiiTivr  still  adheres  to  his  view 
that  myohsematin  is  an  independent  coloring  substance,  and  in  sup- 
port of  his  opinion  he  adduces  the  fact  that  myohaematin  is  found 
also  in  the  muscles  of  insects  in  which  no  hsemoglobin  occurs. 

The  reddish-yellow  coloring  matter  of  the  muscles  of  the  salmon  has  been 
little  studied.  Traces  of  enzymes,  such  as  pepsin  and  diastatic  enzymes,  have 
been  found  in  them.  The  so-called  "  myosin-ferment,"  and  probably  an 
enzyme  producing  lactic-acid  fermentation,  are  also  found  in  these  muscles. 

Extractive  Bodies  of  the  Muscles. 

The  nitrogenized  extractives  consist  chiefly  of  creatin,  in  the 
proportion  of  2-4  p.  m.,  in  the  fresh  muscles  containing  water,  alj;o 
the  xanthin  bodies,  hypoxantJiin  and  xanthin,  besides  guanin  and 
carnin.  The  average  quantity  of  hypoxanthin,  xanthin,  and  guanin 
in  1000  parts  of  the  dried  substance  of  the  muscles  of  oxen  is, 
according  to  Kossel,  respectively  2.30,  0.53,  and  0.20  grms.,  and  in 
the  embryonic  ox-muscles  respectively  3.59,  1.11,  and  4.12  grms. 

Besides  these  we  must  also  consider  as  an  extractive  body  the  syrupy  inosie 
acid  (CoHiiNiOii),  of  which  only  traces  are  found  in  certain  animals.  This 
acid  was  first  prepared  by  Liebig,  but  not  closely  studied.  Limpricht  has 
found  another  in  the  flesh  of  certain  cyprindea,  namely,  the  nitrogenized  ?>rotoc 
acid.  Uric  acid,  urta,  taurin,  and  leucin  are  found  as  traces  in  the  muscles  in 
certain  cases  only,  in  a  few  species  of  animals.  In  regard  to  the  amount  of 
these  different  extractives  in  the  muscles,  Kri^kenberg  and  Wagnek  have 
shown  that  it  varies  greatly  in  different  animals.  A  large  amount  of  urea  is 
found  in  the  muscles  of  the  shark  and  ray  ;  uric  acid  is  found  in  alligators  ; 


MUSCLE.  257 

taurin  in  cephalopoda  ;  glycocoU  in  mollusks,  pecteu  irradians  ;  and  creatinin 
in  luvarus  imperialis,  etc.,  etc. 

The  xanthin  bodies,  with  the  exception  of  carnin,  have  been 
treated  on  pages  47-53,  and  therefore  among  the  extractive  bodies 
we  will  first  consider  the  discussion  of  creatin. 

Creatin,  C1H9N3O2  +  H3O  or  methylguan"idin"-acetic  acid, 
NH:C(NH2).N(CH3).CH2.COOHH-H20,  occurs  in  the  muscles  of 
vertebrate  animals  in  variable  amounts  in  different  species  ;  the 
largest  amount  is  found  in  birds.  It  is  also  found  in  the  brais, 
blood,  transudations,  and  the  amniotic  fluid.  Creati)!  may  be  pre- 
pared synthetically  from  cyauamid  and  sarcosine  (methylglycocoll). 
On  boiling  with  baryta-water  it  decomposes,  with  the  addition  of 
water,  and  yields  urea,  sarcosine,  and  certain  other  products.  Be- 
cause of  this  behavior  several  investigators  consider  creatin  as  a 
step  in  the  formation  of  urea  in  the  organism.  On  boiling  with 
acids  creatin  is  easily  converted,  with  the  elimination  of  water,  into 
creatinin,  which  occurs  in  urine,  and  which  has  also  been  found  in 
the  muscles  of  the  dog  by  Monari  (see  Chapter  XIV), 

Creatin  crystallizes  in  hard,  colorless,  monoclinic  prisms  which 
lose  their  water  of  crystallization  at  100°  C.  It  dissolves  in  74 
parts  of  water  at  the  ordinary  temperature  and  9410  parts  abso- 
lute alcohol.  It  dissolves  more  easily  with  the  aid  of  heat.  Its 
watery  solution  has  a  neutral  reaction.  Creatin  is  not  dissolved  by 
ether.  If  a  creatin  solution  is  boiled  with  precipitated  mercuric 
oxide,  this  is  reduced  to  mercury  and  oxalic  acid,  and  the  disgust- 
ing-smelling methyluramin  (methylguanidin)  is  developed.  A 
solution  of  creatin  in  water  is  not  precipitated  by  basic-lead  acetate 
but  gives  a  white,  flaky  precipitate  with  mercurous  nitrate.  When 
boiled  for  an  hour  with  dilute  hydrochloric  acid  creatin  is  con- 
verted into  creatinin,  and  may  be  identified  by  its  reactions. 

The  preparation  and  detection  of  creatin  is  best  performed  by 
the  following  method  of  Neubauer,  which  was  .first  used  in  the 
preparation  of  creatin  from  muscles.  Finely-cut  flesh  is  extracted 
with  an  equal  weight  of  water  at  +  55°  to  60°  C.  for  10-15  minutes, 
pressed  and  extracted  again  with  water.  The  albumin  is  removed 
from  the  united  extracts  as  far  as  possible  by  coagulation  at  boiling 
heat,  the  filtrate  precipitated  by  the  careful  addition  of  basic-lead 
acetate,  the  lead  removed  from  this  filtrate  by  HgS  and  carefully 
ooncentrated  to  a. small  volume.     The  creatiu,  which  crystallizes  in 


258  PHYSIOLOGICAL   CHEMISTBT. 

a  few  days,  is  collected  on  a  filter,  washed  with  alcohol  of  88^,  and 
purified,  when  necessary,  by  recrystallization.  The  quantitative 
estimation  of  creatin  is  performed  according  to  the  same  method. 

Carnin,  C7H8N4O3  -|-  H2O,  is  one  of  the  substances  found  by  Weidbl  in 
American  meat  extract.  It  has  also  been  found  by  Kkukenberg  and  Wag- 
ner in  frog-muscles  and  in  the  flesh  of  fish,  and  by  Pouchet  in  urine.  As 
previously  stated  (page  48),  carnin  may  be  converted  into  hypoxanthin  by 
meaus  of  oxidation. 

Carnin  has  been  obtained  as  a  white  crystalline  mass.  It  dissolves  with 
difficulty  in  cold  water,  but  dissolves  easily  in  warm.  It  is  insoluble  in  alco- 
hol and  ether.  It  dissolves  in  warm  hydrochloric  acid  and  yields  a  salt  crys- 
tallizing in  shining  needles,  which  gives  a  double  combination  with  platinum 
chloride.  Its  watery  solution  is  precipitated  by  silver  nitrate,  but  this  precipi- 
tate is  neither  dissolved  by  ammonia  nor  by  warm  nitric  acid.  Carnin  does 
not  give  the  so-called  Weidel's  xanthin  reaction.  Its  watery  solution  is 
precipitated  by  basic- lead  acetate ;  still  the  lead  combinations  may  be  dissolved 
on  boiling. 

We  must  also  include  among  the  nitrogenized  extractives  those  bodies 
which  vrere  discovered  by  Gautier,  and  which  occur  in  very  small  quan- 
tities, namely,  the  leucomaines  :  xanthocreatinin,  C5H10N4O,  crusocreatinin, 
C6H8N4O,  ampMcreatin,  C9H19N7O4 ,  and  pseudoxanthin,  C4H6N5O. 

The  non-nitrogenized  extractive  bodies  of  the  muscles  are 
inosit,  glycogen,  sugar,  and  lactic  acid. 

Inosit,  CgHigOs  +  HgO.  This  body,  discovered  by  Scherek,  is 
not  a  carbohydrate,  but  belongs  to  the  aromatic  series  and  seems 
to  be  hexahydroxybenzol  (Maqueiste'e).  With  hydroiodic  acid 
it  yields  benzol  and  tri-iodophenol,  and  on  oxidation  with  nitric 
acid,  tetra-oxychinon.  Inosit  is  found  in  the  muscles,  liver,  spleen, 
kidneys,  super-renal  cavity,  lungs,  brain,  testicles,  and  in  the  urine 
in  pathological  cases.  It  is  found  very  widely  distributed  in  the 
vegetable  kingdom,  especially  in  unripe  fruits,  in  green  beans, 
{phaseolus  vulgaris),  and  therefore  it  is  also  called  phaseomakhit. 

Inosit  crystallizes  in  large,  colorless,  rhombical  crystals  of  the 
monoclinic  system,  or,  if  not  pure  and  if  only  a  small  quantity 
crystallizes,  it  forms  groups  of  fine  crystals  similar  to  cauliflower. 
It  looses  its  water  of  crystallization  at  110°  C,  also  if  exposed  to 
the  air  for  a  long  time.  Such  exposed  crystals  are  non-transparent 
and  milk-white.  The  crystals  melt  at  217°  0.  Inosit  dissolves  in 
six  parts  of  water  at  ordinary  temperature,  and  the  solution  has  a 
sweetish  taste.  It  is  insoluble  in  strong  alcohol  and  in  ether. 
Inosit  does  not  ferment  with  beer-yeast;  it  dissolves  copper  oxyhy- 
drate  in  alkaline  solutions,  but  does  not  reduce  on  boiling.  It  gives 
negative  results  with  Moore's  or  Bottger-Almen^'s  bismuth  tests. 


MUSCLE.  259 

If  inosit  is  evaporated  to  dryness  on  a  platinum  foil  with  nitric 
acid  and  the  residue  treated  with  ammonia  and  a  drop  of  calcium- 
chloride  solution  and  carefully  re-evaporated  to  dryness,  a  beautiful 
rose-red  residue  is  obtained  (Scherek's  inosit  test).  If  we  evapo- 
rate an  inosit  solution  to  incipient  dryness  and  moisten  the  residue 
with  a  little  mercuric-nitrate  solution,  we  obtain  a  yellowish  residue 
on  drying,  which  becomes  a  beautiful  red  on  strongly  heating. 
The  coloration  disappears  on  cooling,  but  it  reappears  on  gently 
warming  (Gallois's  inosit  test). 

To  prepare  inosit  from  a  liquid  or  from  a  watery  extract  of  a 
tissue,  the  albumin  is  first  removed  by  coagulating  at  boiling  heat. 
The  filtrate  is  precipitated  by  sugar  of  lead,  this  filtrate  boiled  with 
basic-lead  acetate  and  allowed  to  stand  24-48  hours.  The  j^recipi- 
tate  thus  obtained,  which  contains  all  the  inosit,  is  decomposed  in 
water  by  HaS.  The  filtrate  is  strongly  concentrated,  treated  with 
2-4  vols,  hot  alcohol,  and  the  liquid  removed  as  soon  as  possible  from 
the  tough  or  flaky  masses  which  ordinarily  separate.  If  no  crystals 
separate  from  the  liquid  within  24  hours,  then  treat  with  ether  until 
the  liquid  has  a  milky  appearance  and  allow  it  to  stand.  In  the 
presence  of  a  sufficient  quantity  of  ether,  crystals  of  inosit  separate 
within  24  hours.  The  crystals  thus  obtained,  as  also  those  which 
are  obtained  from  the  alcoholic  solution  directly,  are  recrystallized 
by  redissolving  in  very  little  boiling  water  and  the  addition  of 
3-4  vols,  alcohol. 

Glycogen  is  a  constant  constituent  of  the  living  muscle,  while  it 
may  be  absent  in  the  dead  muscle.  The  amount  of  glycogen  varies 
in  the  different  muscles  of  the  same  animal.  Bohm  found  10  p.  m. 
glycogen  in  the  muscles  of  cats,  and  moreover  he  found  a  greater 
amount  in  the  muscles  of  the  extremities  tha#in  those  of  the  rump. 
Gri'Tzxer  obtained  more  glycogen  from  the  white  muscles  of 
mammalia  than  from  the  red  ones.  The  food  also  has  a  great  influ- 
ence. Bohm  found  1-4  p.  m.  glycogen  in  the  muscles  of  fasting 
animals  and  7-10  p.  m.  after  partaking  of  food.  Luchsinger 
maintains  an  opinion,  formerly  generally  accepted,  that  in  starvation, 
or  if  there  is  a  lack  of  carbohydrates  in  the  food,  glycogen  disap- 
pears more  quickly  from  the  muscles  than  from  the  liver;  but  ac- 
cording to  Aldehoff,  exactly  the  reverse  takes  place.  The  glyco- 
gen disappears  more  quickly  in  starvation  from  the  liver  than  from 
the  muscles,  not  only  in  hens,  as  observed  by  "Weiss,  but  also  in 
other  animals,  such  as  the  pigeon,  rabbit,  cat,  and  horse. 


260  PHYSIOLOGICAL   CHEMISTRT. 

Muscle-sugar,  of  which  traces  only  occur  in  the  living  muscle 
and  which  is  probably  formed  after  the  death  of  the  muscle  from 
the  muscle-glycogen,  is  perhaps  grape-sugar  (glucose).  As  an  inter- 
mediate step  in  this  sugar  formation  we  must  mention  dextrin, 
which  is  sometimes  found  in  the  muscles.  Perhaps  this  dextrin  has 
been  confounded  with  glycogen. 

Lactic  Acids.  Of  the  four  acids  of  the  formula  CaHgOa  there  is 
one,  hydracrylic  acid,  which  is  not  found  in  the  animal  organism. 
The  statements  as  to  the  occurrence  of  another,  ethylen  lactic 
acid  (in  meat  extract),  are  disputed.  Etliidene  lactic  acid, 
CH3.  CH(OH).COOH,  is  of  physiologico-chemical  importance. 
Two  modifications  occur — the  optically  inactive  fbkmentation' 
LACTIC  ACID,  and  the  optically   active,  dextro-gyrate  paralactio 

ACID,  or  SARCOLACTIC  ACID. 

T'hQ  fermentation  lactic  acid,  which  is  formed  from  milk-sugar 
by  allowing  milk  to  sour  and  by  the  acid  fermentation  of  other 
carbohydrates,  is  considered  to  exist  in  small  quantities  in  the 
muscles  (Heintz),  in  the  gray  matter  of  the  brain  (Gscheidlen), 
and  in  diabetic  urine.  During  digestion  this  acid  is  also  found  in 
the  contents  of  the  stomach  and  intestines,  and  as  alkali  lactate 
in  the  chyle.  The  paralactic  acid  is,  at  all  events,  the  true  acid  of 
meat  extracts,  and  this  alone  has  been  found  with  certainty  in  dead 
muscle.  That  lactic  acid  which  is  found  in  the  spleen,  lymphatic 
glands,  thymus,  thyroid  gland,  blood  (traces),  bile,  pathological 
transudations,  osteotnalicous  bones,  in  perspiration  in  puerperal 
fever,  and  in  the  urine  after  excessive  marches,  in  acute  yellow 
atrophy  of  the  liver,  ill  poisoning  by  phosporus,  especially  after 
extirpation  of  the  liver  (in  geese,  according  to  Minkowski,  in  frogs 
by  Marcuse  and  Werther),  seems  to  be  paralactic  acid. 

The  lactic  acids  are  amorphous.  They  have  the  appearance  of 
colorless  or  faintly  yellowish,  acid-reacting  syrups  which  mix  in  all 
proportions  with  water,  alcohol,  or  ether.  The  salts  are  soluble  in 
water,  and  most  of  them  in  alcohol.  The  two  acids  are  differenti- 
ated from  each  other  by  their  different  optical  properties — paralactic 
acid  being  dextro-gryate,  while  fermentation  lactic  acid  is  optically 
inactive — also  by  their  different  solubilities  and  the  different 
amounts  of  water  of  crystallization  of  the  calcium  and  zinc  salts. 
The  zinc  salt  of  fermentation  lactic  acid  dissolves  in  58-63  parts  of 


MUSCLE.  261 

water  at  14°-15°  C.  and  contains  18.18^  water  of  crystallization,  cor- 
responding to  the  formula  Zn(C3H503)2  +  SHjO.  The  zinc  salt  of 
paralactic  acid  dissolves  in  17.5  parts  of  water  at  the  above  temper- 
ature and  contains  ordinarily  12,9^  water,  corresponding  to  the 
formula  Zn(C3H503)2  +  2H2O.  The  calcium  salt  of  fermentation 
lactic  acid  dissolves  in  9.5  parts  water  and  contains  29.22<^ 
(=5  mol.)  water  of  crystallization,  while  the  calcium  paralactate 
dissolves  in  12.4  parts  water  and  contains  24.83  or  26.21^  (=4or4| 
mol.)  water  of  crystallization.  Both  calcium  salts  crystallize,  not 
unlike  tyrosin  in  spheres  or  tufts  of  very  fine  microscopic  needles. 

Lactic  acids  may  be  detected  in  organs  and  tissues  in  tlie  follow- 
ing manner:  After  complete  extraction  with  water  the  albumin  is 
removed  by  coagulation  at  boiling  temperature  and  the  addition  of 
a  small  quantity  of  sulphuric  acid.  The  liquid  is  then  exactly 
neutralized  while  boiling  with  caustic  baryta,  and  then  evaporated 
to  a  syrup  after  filtration.  The  residue  is  precipitated  with  absolute 
alcohol,  and  the  precipitate  completely  extracted  with  alcohol. 
The  alcohol  is  entirely  distilled  from  the  united  alcoholic  extracts, 
and  the  neutral  residue  is  shaken  with  ether  to  remove  the  fat. 
The  residue  is  taken  up  by  water  and  phosphoric  acid  added,  and 
repeatedly  shaken  with  fresh  quantities  of  ether,  which  dissolve  the 
lactic  acid.  The  ether  is  now  distilled  from  the  several  ethereal 
extracts,  the  residue  dissolved  in  water,  and  this  solution  carefully 
warmed  on  the  water-bath  to  remove  the  last  traces  of  ether  and 
volatile  acids.  A  solution  of  zinc  lactate  is  prepared  from  this 
filtered  solution  by  boiling  with  zinc  carbonate,  and  this  is  evapo- 
rated until  crystallization  commences  and  then  allowed  to  stand 
over  sulphuric  acid. 

Fat  is  never  absent  in  the  muscles.  Some  fat  is  always  found  in 
the  inter-muscular  connective  tissue;  but  the  muscle-fibres  them- 
selves also  contain  fat.  The  amount  of  fat  in  the  real  muscle  sub- 
stance is  always  small,  usually  amounting  to  about  10  p.  m.  or 
somewhat  more.  A  considerable  amount  of  fat  in  the  muscle-fibres 
is  only  found  in  fatty  degeneration.  Lecithin  is  also  habitually 
found  in  the  muscles. 

The  Mineral  Bodies  of  the  Muscles.  We  have  no  complete 
analyses  of  the  mineral  substances  of  the  pure,  blood-free  muscle 
substance.  The  ash  remaining  after  burning  the  muscle,  which 
amounts  to  about  10-15  p.  m.,  calculated  on  the  moist  muscle,  is 
acid  in  reaction.     The  largest  constituents  are  potassium  and  phos- 


262  PHYSIOLOGICAL  CHEMISTRY. 

phoric  acid.  Next  in  amount  we  have  sodium  and  magnesium,  and 
lastly  calcium,  chlorine,  and  iron  oxide.  Sulphates  only  exist  as 
traces  in  the  muscles,  but  are  formed  by  the  burning  of  the  proteids 
of  the  muscles,  and  therefore  occur  in  abundant  quantities  in  the 
ash.  The  muscles  contain  such  a  large  quantity  of  potassium  and 
phosphoric  acid  that  potassium  phosphate  seems  to  be  unquestion- 
ably the  predominating  salt.  Chlorine  is  found  in  such  insignifi- 
cant quantities  that  it  is  perhaps  derived  from  a  contamination  with 
blood  or  lymph.  The  quantity  of  magnesium  is  about  double  that 
of  calcium.  These  two  bodies,  as  well  as  iron,  occur  only  in  very 
small  amounts. 

The  gases  of  the  muscles  consist  of  large  quantities  of  carbon 
dioxide,  besides  traces  of  nitrogen. 

Rigor  Mortis  of  the  Muscles.  If  the  influence  of  the  circulating^ 
oxygenated  blood  is  removed  from  the  muscles,  as  after  death  of 
the  animal  or  by  tying  the  aorta  or  the  muscle-arteries  (Steit- 
son's  test),  rigor  mortis,  sooner  or  later  takes  place.  The  ordinary 
rigor  appearing  under  these  circumstances  is  called  the  spontaneous 
or  the  fermentive  rigor,  because  it  seems  to  depend  in  part  on  the 
action  of  an  enzyme.  A  muscle  may  also  become  stiff  for  other 
reasons.  The  muscles  may  become  momentarily  stiff  by  warming, 
in  the  case  of  frogs  to  40°,  in  mammalia  to  48°-50°,  and  in  birds 
to  53°  C.  (heat-rigor).  Distilled  water  may  also  produce  a  rigor  in 
the  muscles  (water-rigor).  Acids,  even  when  very  weak,  such  as 
carbon  dioxide,  may  quickly  produce  a  rigor  (acid-rigor),  or  hasten 
its  appearance.  A  number  of  chemically  different  substances,  such 
as  chloroform,  ether,  alcohol,  ethereal  oils,  caffein,  and  many  alka- 
loids, produce  a  similar  effect.  That  rigor  which  is  produced  by 
means  of  acids  or  other  agents  which,  like  alcohol,  coagulate 
albumin  must  be  considered  as  produced  by  entirely  different  pro- 
cesses than  the  spontaneous  rigor. 

The  time  within  which  the  spontaneous  rigor  occurs  depends 
upon  the  temperature;  a  low  temperature  retarding  and  a  high 
temperature  hastening  its  appearance.  Muscular  activity  also  exer- 
cises an  appreciable  influence  on  the  rigor  of  the  muscles,  for  a 
previous  active  contraction  accelerates  the  rigor  of  the  muscles;  the 
mechanical  abuse  of  the  muscles  acts  in  the  same  way.  The  appear- 
ance of  spontaneous  rigor  is  under  the  influence  of  the  central  nerv- 


MUSCLE.  263 

ous  system,  and  a  muscle  whose  nerve  has  been  severed  stiffens 
more  slowly  than  one  whose  continuity  with  the  central  nervous 
system  has  not  been  destroyed  (HERMANisr  and  his  pupils  v.  Eisel- 
BERG,  V.  Gender  and  Bierfrbund).  The  nervous  system  seems 
also  to  have  a  similar  influence  on  the  post-mortem  acidification  of 
the  muscles  (Gross).  Hermann  and  his  pupils  consider  the  rigor 
mortis  as  a  slowly-proceeding  muscular  contraction,  identical  with 
the  ordinary  muscular  contraction,  but  it  is  difl&cult  at  this  time 
to  determine  as  to  the  correctness  of  this  view  from  a  chemical 
standpoint. 

When  the  muscle  passes  into  7-igor  mortis  it  becomes  shorter  and 
thicker,  harder  and  non-transparent,  less  ductile  and  acid.  The 
chemical  processes  which  take  place  in  this  step  are  the  following  : 
By  the  coagulation  of  the  plasma  a  myosin-clot  is  produced  which 
is  the  cause  of  the  hardening  and  of  the  diminished  transparency 
of  the  muscle.  The  appearance  of  this  clot  may  be  hastened  by  the 
simultaneous  occurrence  of  lactic  acid.  Carbon  dioxide  is  also 
formed,  Avhich  does  not  seem  to  be  a  direct  oxidation  product. 
Hermann  claims  that  carbon  dioxide  is  produced  in  the  removed 
muscle,  even  in  the  absence  of  oxygen,  when  it  passes  into  rigor 
mortis.  The  quantity  of  carbon  dioxide  and  lactic  acid  produced 
on  the  acidification  of  the  muscle  is  not  dependent  upon  the  quick- 
ness or  slowness  of  the  rigor  tnortis  (Ranke,  Hermann).  It  is  not 
known  from  what  mother-substance  these  acids  are  formed.  The 
most  probable  explanation  is  that  carbon  dioxide  and  lactic  acid  are 
produced  from  glycogen,  and  the  fact  that  the  glycogen  in  the 
muscle  decreases  on  stiffening  has  been  asserted  positively  (Nasse, 
Werther).  On  the  other  side,  Bohm  has  shown  that  cases  are 
found  in  which  the  glycogen  is  not  diminished  on  stiffening,  and  he 
has  also  found  that  the  quantity  of  lactic  acid  produced  is  not  pro- 
portional to  the  quantity  of  glycogen.  Under  these  circumstances, 
as  the  muscles  of  starving  pigeons,  which  are  free  from  glycogen, 
yield,  according  to  Damant,  lactic  acid  after  death,  it  is  hardly 
possible  that  the  two  above  acids  are  formed  from  glycogen.  The 
only  remaining  explanation  is  that  they  originate  from  the  proteids 
or  certain  other  not  well-known  constituents  of  the  muscles. 

After  the  muscles  have  been  stiff  for  some  time  they  relax 
again  and  become  softer.     This  may  partly  depend  on  their  becom- 


264  PHYSIOLOGICAL  CHEMI8TRT. 

ing  strongly  acid  and  the  myosin-clot  dissolving  in  the  acid,  and 
partly,  and  in  all  probability  mainly,  upon  a  putrefaction. 

Exchange  of  Material  in  the  Inactive  and  Active  Muscles.  It  is 
admitted  by  a  number  of  prominent  investigators,  Pfluger  and 
CoLASANTi,  ZuNTZ  and  EoHRiG,  and  others,  that  the  exchange  of 
material  in  the  muscles  is  regulated  by  the  nervous  system. 
When  at  rest,  when  there  is  no  mechanical  exertion,  we  have  a 
condition  which  Zuntz  and  Eohrig  have  designated  "chemical 
tonus."  This  tonus  seems  to  be  a  reflex  tonus,  for  it  may  be  re- 
duced by  discontinuing  the  connection  between  the  muscles  and 
the  central  organ  of  the  nervous  system  by  cutting  through  the 
spinal  marrow  or  the  muscle-nerves,  or  by  paralyzing  the  same  by 
means  of  curara  poison.  It  may  also  be  reduced  or  checked  by 
adjusting  the  temperature  between  the  skin  and  the  surrounding 
medium;  or  it  maybe  increased  by  the  reverse,  by  irritating  the 
nerves  of  the  skin  by  cooling.  The  possibility  of  reducing  the 
chemical  tonus  of  the  muscles  by  any  of  the  above-mentioned 
means,  but  especially  by  the  action  of  curara,  oSers  an  important 
means  of  deciding  the  extent  and  kind  of  chemical  processes  going 
on  in  the  muscles  when  at  rest.  In  comparative  chemical  investi- 
gation of  the  processes  in  the  active  and  in  the  inactive  muscles 
several  ways  of  procedure  have  been  adopted.  The  removed 
homologous,  active  and  inactive  muscles  have  been  compared,  also 
the  arterial  and  venous  muscle-blood  in  rest  and  in  activity,  and 
lastly  the  total  exchange  of  material,  the  receipts  and  expenditures 
of  the  organism,  have  been  investigated  under  these  two  conditions. 

By  investigations  according  to  these  several  methods,  it  has 
been  found  that  the  active  muscle  takes  up  oxygen  from  the  blood 
and  returns  to  it  carbon  dioxide,  and  also  that  the  quantity  of 
oxygen  taken  up  is  greater  than  the  oxygen  contained  in  the  car- 
bon dioxide  eliminated  at  the  same  time.  The  muscle,  therefore, 
holds  in  some  form  of  combination  a  part  of  the  oxygen  taken  up 
while  at  rest.  During  activity  the  exchange  of  material  in  the 
muscle,  and  therewith  the  exchange  of  gas,  is  increased.  The 
animal  organism  takes  up  considerably  more  oxygen  in  activity 
than  when  at  rest,  and  eliminates  also  considerably  more  carbon 
dioxide  (Regfatilt  and  Eeiset  and  others).  The  quantity  of 
oxygen  which  leaves  the  body  as  carbon  dioxide  is,  during  activity. 


MUSCLE.  265 

considerably  larger  than  the  quantity  of  oxygen  taken  up  at  the 
same  time;  and  the  venous  muscle-blood  is  poorer  in  oxygen  and 
richer  in  carbon  dioxide  during  activity  than  during  rest  (Ludwig 
and  SczELKOW  and  others).  The  exchange  of  gases  in  the  muscles 
during  activity  is  the  reverse  to  when  at  rest,  for  the  active  muscle 
gives  up  a  quantity  of  carbon  dioxide  which  does  not  correspoud 
to  the  quantity  of  oxygen  taken  up,  but  is  considerably  greater. 
It  :follows  from  this  that  in  muscular  activity  not  only  oxidation 
takes  place,  but  also  splitting  processes.  This  follows  also  from  the 
fact  that  removed  blood-free  muscles,  when  placed  in  an  atinos- 
phere  devoid  of  oxygen,  can  labor  for  some  time  and  also  yield  car- 
bon dioxide  (Heemann). 

During  muscular  inactivity  a  consumption  of  glycogen  takes 
place.  This  is  inferred  from  the  observations  of  several  investiga- 
tors that  the  quantity  of  glycogen  is  increased  and  its  correspond- 
ing consumption  reduced  in  those  muscles  whose  chemical  tonus  is 
lowered  either  by  cutting  through  the  nerve  or  for  other  reasons 
(Bernard,  McDonnel,  Chandelon,  and  others.  After  cutting 
the  nerve  Makche  obtained  no  doubtful  results).  In  activity  this 
consumption  of  glycogen  is  increased,  a7id  it  has  been  positively 
proved  by  the  researches  of  several  investigators  (Nasse,  BRtfcKE 
and  Weiss,  Kulz,  Marcuse,  Manche)  that  the  quantity  of  gly- 
cogen in  the  muscles  in  activity  quickly  and  abundantly  decreased. 
By  investigating  with  the  muscles  in  situ,  especially  on  the  levator 
labii  superioris  of  a  horse,  Chauveau  and  Kaufmann"  have  not 
only  confirmed  the  above  facts  in  regard  to  the  exchange  of  gas 
during  rest  and  activity,  but  they  also  found  that  the  muscles 
remove  sugar  from  the  blood,  and  indeed  considerably  more  during 
activity  than  when  at  rest.  They  found  (calculating  the  amount 
found  in  1  gramme  of  muscle  per  minute  to  1  kilo  per  hour)  that 
1  kilo  of  muscle  removes  2.186  grms.  sugar  from  the  blood  i^er 
hour  during  rest,  while  it  removes  8.416  grms.  per  hour  in  activity. 
Qtjikqtjaud  has  also  observed  a  consumption  of  sugar  from  the 
blood  during  activity.  On  comparing  the  amount  of  carbon  which 
the  muscles  remove  from  the  blood  as  sugar  with  the  amount  they 
give  off  as  carbon  dioxide,  Chauveau  and  Kaufmann  found  that 
in  rest  more  carbon  was  taken  up  than  given  off,  while  during 
activity  this  condition  was  reversed.     From  these  facts  it  is  claimed 


266  PHYSIOLOGICAL   CHEMISTRY. 

by  them  that  during  rest  glycogen  is  formed  from  the  sugar,  and 
also  that  in  activity  other  bodies  besides  sugar  are  transformed  in 
the  muscles. 

The  faintly  alkaline  or  amphoteric  reaction  of  the  inactive 
muscles  is  changed  during  activity  to  an  acid  reaction  (DuBois- 
Eetmond  and  others),  and  the  acid  reaction  to  a  certain  point 
increases  with  the  work  (Heidenhain).  The  quickly-contracting 
pale  muscles  produce,  according  to  Gleiss,  more  acid  during  ac- 
tivity than  the  more  slowly-contracting  red  muscles.  The  acid 
reaction  appearing  during  activity  was  formerly  considered  due  to 
the  formation  of  lactic  acid,  a  view  which  has  been  contradicted  by 
ASTASCHEWSKY,  Pelugee  and  Waree^s",  who  found  less  lactic  acid 
in  the  tetanized  muscle  than  when  at  rest.  According  to  the 
recent  and  more  carefully  conducted  investigations  of  Marcuse, 
which  have  since  been  confirmed  by  Werthee,  there  is  no  doubt 
that  free  lactic  acid  is  actually  produced  in  the  muscle  during 
activity.  According  to  Weyl  and  Zeitlee,  the  active  muscle  con- 
tains a  larger  amount  of  phosphoric  acid  (formed  at  least  in  part 
from  the  decomposition  of  lecithin)  than  the  resting  muscle;  and 
the  acid  reaction  of  the  active  muscle  may,  therefore,  in  part  be 
due  to  the  acid  phosphate. 

The  amount  of  albumin  in  the  removed  muscles  is,  according  to 
Eanke  and  Naweocki,  decreased  by  work.  The  correctness  of 
this  statement  is,  however,  disputed  by  other  investigators.  Also 
the  older  statements  in  regard  to  the  nitrogenized  extractive  bodies 
of  the  muscle  in  rest  and  in  activity  are  uncertain.  According  to  the 
recent  researches  of  Mo]srAEi,  the  total  quantity  of  creatin  and 
creatinin  is  increased  by  work;  and  indeed  by  an  excess  of  muscular 
activity,  the  amount  of  creatinin  is  especially  augmented.  The 
creatinin  is  formed  essentially  from  the  creatin.  In  excessive 
activity  Mokaei  also  found  xautho-creatinin  in  the  muscle,  and 
the  quantity  was  one  tenth  of  that  of  the  creatinin.  The  quantity 
of  xanthin  bodies  is,  according  to  Mon^aei,  decreased  under  the 
influence  of  work.  It  seems  to  have  been  positively  shown  that  the 
active  muscle  contains  a  smaller  quantity  of  bodies  soluble  in 
water  and  a  larger  quantity  of  bodies  soluble  in  alcohol  than  the 
resting  muscle  (Helmholtz). 

An  attempt  has  been  made  to  solve  the  question  relative  to  the 


MUSCLE.  267 

behavior  of  the  nitrogenized  constituents  of  the  muscle  at  rest 
and  during  activity,  by  determining  the  total  quantity  of  nitrogen 
eliminated  under  these  different  conditions  of  the  body.  While 
we  in  the  past  agreed  with  the  views  of  Liebig  that  the  elimination 
of  nitrogen  by  the  urine  was  increased  by  muscular  work,  the 
researches  of  several  experimenters,  especially  those  of  V^oit  on 
dogs  and  VoiT  and  Pettexkofer  on  man,  have  led  to  quite  differ- 
ent results.  They  have  shown  that  during  work  no  increase  or  only 
a  very  insignificant  increase  in  the  elimination  of  nitrogen  takes  place. 
"We  must  not  conceal  the  fact  that  we  have  a  series  of  experiments 
which  show  a  significant  increase  in  the  exchange  of  proteids  during 
or  after  work.  We  have  as  example  the  observations  of  Flint  ^ 
and  Payt  on  a  pedestrian,  v.  Wolff,  v.  Fujtke,  Kreuzhage 
and  Kellxer  on  a  horse,  and  lately  those  of  Argutinskt  on  him- 
self, which  show  an  undoubted  increase  in  the  elimination  of 
nitrogen  during  or  after  work. 

The  elimination  of  nitrogen  is  mainly  dependent  upon  causes 
which  will  be  spoken  of  later  (Chapter  XV),  such  as  the  quantity 
and  composition  of  the  food,  the  condition  of  the  adipose  tissue, 
the  action  of  work  on  the  respiratory  mechanism,  etc.,  etc.,  all  of 
which  can  hardly  have  received  sufficient  consideration  in  the  last- 
mentioned  experiments.  The  strong  proof  which  the  very  careful 
experiments  of  Yoit  and  of  Pettenkofer  and  Yoit  furnish  in 
support  of  this  theory  is  hardly  destroyed  by  these  investigations; 
though  we  must  admit  that  this  question  is  still  somewhat  unsettled. 
Even  if  we  consider  that  muscular  work  does  not  cause  any 
increase  in  the  elimination  of  nitrogen,  which  has  been  quite  posi- 
tively proved,  still  we  do  not  exclude  the  possibility  of  an  increased 
exchange  of  proteids  in  the  muscle.  It  is  possible  on  account  of 
the  functional  exchange  action  of  the  organs,  of  which  Eanke  has 
made  a  special  study,  that  an  increased  exchange  of  proteid  in  the 
muscles  may  be  compensated  by  a  simultaneous  decreased  exchange 


'  The  results  obtained  by  Prof.  A.  Flint  were  derived  from  experi- 
ments made  upon  the  pedestrian  Weston,  who  in  1870,  in  the  American  Insti- 
tute Building  (New  York),  travelled  a  distance  of  317^  miles  in  five  days. 
The  chemical  part  of  the  work  was  performed  under  the  immediate  supervision 
of  Prof.  R.  O.  DoREMtrs.  For  fifteen  days,  five  before,  five  during,  and  five 
after  the  walk,  all  ingesta  and  excreta  were  weighed  or  measured  and  analyzed. 
The  experiments  of  Dr.  Pavy  were  made  in  London  in  1876. — Translator. 


268  PHYSIOLOGICAL  CHEMISTRY. 

of  proteid  in  other  organs.  But  however  this  may  be,  the 
modern  view  is,  notwithstanding,  that  the  exchange  of  proteid  in 
the  muscle  is  not  increased  by  activity. 

The  investigations  on  the  amount  of  fat  in  removed  muscles 
during  activity  and  at  rest  liave  not  led  to  any  definite  results. 
The  experiments  of  Voit  on  a  starving  dog,  and  those  of  Petten- 
KOFEE,  and  Voit  on  a  man,  offer  strong  proofs  to  show  that  an 
increased  decomposition  of  the  fat  takes  place  during  activity. 

If  the  results  from  the  investigations  thus  far  made  of  the 
chemical  processes  going  on  in  the  active  and  inactive  muscle  were 
collected  together,  we  should  find  the  following  characteristics  for 
the  active  muscle.  The  active  muscle  takes  up  more  oxygen  and 
gives  off  more  carbon  dioxide  than  the  inactive  muscle;  still  the 
elimination  of  carbon  dioxide  is  increased  considerably  more  than 
the  absorption  of  oxygen.  In  work  a  consumption  of  carbohydrates, 
glycogen,  and  sugar  takes  place.  A  consumption  of  sugar  seems 
only  to  have  been  shown  in  muscle  with  blood  circulation,  while  a 
consumption  of  glycogen  also  has  been  observed  in  removed  muscle. 
Lactic  acid  is  formed  in  activity,  which  is  carried  off  by  the  blood 
and  taken  up  and  consumed  by  the  liver.  Acid-alkali  phosphates 
also  seem  to  be  produced  by  work.  In  regard  to  the  behavior  of 
fats  in  removed  muscles  nothing  is  known  with  certainty,  though  an 
increase  in  the  consumption  of  fat  in  the  organism  has  been  ob- 
served during  activity.  An  increase  in  the  nitrogenized  extractive 
bodies  of  the  creatin  group  seems  also  to  occur.  In  regard  to  the 
albuminous  bodies  the  views  are  contradictory;  but  an  increased 
elimination  of  nitrogen  as  a  direct  consequence  of  muscular  exer- 
tion has  thus  far  not  been  positively  proved. 

In  close  connection  with  the  above-mentioned  facts  we  have  the 
question  as  to  the  origin  of  muscular  activity  so  far  as  it  has  its 
origin  in  chemical  processes.  In  the  past  the  generally-accepted 
opinion  was  that  of  Liebig,  that  the  source  of  muscular  action  con- 
sisted of  a  metabolism  of  the  albuminous  bodies;  to-day  another 
view  prevails.  Fick  and  Wislicen'us  climbed  the  Faulhorn  and 
calculated  the  amount  of  mechanical  force  expended  in  the  attempt. 
With  this  they  compared  the  mechanical  equivalent  transformed  in 
the  same  time,  from  the  proteids,  calculated  from  the  nitrogen 
eliminated  with  the  urine,  and  found  that  the  work  really  performed 


MUSCLE.  269 

was  not  by  any  means  compensated  by  the  consumption  of  proteid. 
It  was  therefore  proved  by  this  that  albumin  alone  cannot  be  the 
source  of  muscular  activity,  and  that  this  depends  in  great  measure 
on  the  metabolism  of  non-nitrogenized  substances.  Many  other  ob- 
servations have  led  to  the  same  result,  especially  the  experiments  of 
VoiT,  of  Pettexkofer  and  Voit,  and  of  other  investigators,  whose 
experiments  show  that  while  the  elimination  of  nitrogen  remains  un- 
changed, the  elimination  of  carbon  dioxide  during  work  is  very  con- 
siderably increased.  It  is  also  generally  considered  as  positively 
proved,  that  muscular  work  is  produced,  at  least  the  greatest  part, 
by  the  metabolism  of  non-nitrogenized  substances.  Nevertheless 
we  are  not  warranted  in  the  statement  that  muscular  activity  is 
produced  entirely  at  the  cost  of  the  non-nitrogenized  substance,  and 
that  the  albuminous  bodies  are  without  importance  as  a  source  of 
force. 

'Among  the  non-nitrogenized  bodies  we  must  accord  to  carbo- 
hydrates, glycogen,  and  sugar  the  first  place  as  sources  of  force. 
The  fact  that  the  carbohydrates  are  consumed  during  exertion  has 
been  previously  discussed,  and  their  great  importance  as  a  source 
of  activity  is  generally  admitted.  The  most  important  is  glycogen, 
— not  only  that  which  pre-exists  in  the  muscles,  but  also  that  which 
is  contained  by  the  liver  and  conveyed  by  the  blood  to  the  muscles 
as  sugar  to  be  used  in  muscular  work.  If  the  consumption  of 
carbohydrates  in  activity  is  positively  proved,  then  the  question 
arises  whether  the  quantity  of  glycogen  or  carbohydrates  which  is 
at  the  disposition  of  the  muscles  is  sufficient  for  the  development 
of  the  living  force  produced  within  them.  Though  it  is  difficult  to 
give  a  positive  answer  to  this  question,  it  still  seems  certain  that, 
at  least  in  some  particular  cases,  the  carbohydrates  are  not  sufficient 
for  the  development  of  this  force.  According  to  statements  whose 
correctness  cannot  be  doubted,  muscles  free  from  glycogen  can  per- 
form work  (Beknard,  Luchsinger). 

Even  though  no  direct  investigations  on  removed  muscles  have 
shown  any  increase  in  the  consumption  of  fat  during  activity,  still, 
from  the  above-mentioned  experiments  on  the  exchange  of  material, 
we  conclude  that  the  fats  are  also  undoubtedly  sources  of  muscu- 
lar force.  In  regard  to  the  albuminous  bodies  we  have  no  positive 
direct  observations  which  tend  to  establish  the  miportaiice  attrib- 


270  PHYSIOLOGICAL   CHEMISTRY. 

uted  to  them  by  Liebig  in  muscular  activity;  but  when  we  con- 
sider that  from  the  albuminous  bodies  not  only  the  fats  proceed  but 
also  the  carbohydrates,  glycogen,  it  is  difficult  to  see  why  the 
source  of  muscular  force  is  not  in  part  due  to  a  metabolism  of  the 
proteids.  Though  it  is  probable  that  in  work  the  carbohydrates  in 
the  first  place,  and  then  the  fats,  are  consumed  by  an  increased 
exchange,  it  is  therefore  not  improbable  that  the  albuminous  bodies 
also  take  part,  and  that  all  three  chief  groups  of  organic  foods  or 
muscle-constituents  undergo  an  increased  exchange  during  activity 
(Eanke). 

Quantitative  Composition  of  the  Muscle.  A  large  number  of 
analyses  have  been  made  of  the  flesh  of  various  animals  for  purely 
practical  purposes,  in  order  to  determine  the  nutritive  value  of 
different  varieties  of  meat;  but  we  have  no  exact  scientific  analyses 
with  sufficient  regard  to  the  quantity  of  different  albuminous 
bodies  and  the  remaining  muscle-constituents;  or  these  analyses 
being  incomplete  are  of  little  value. 

To  give  the  reader  some  idea  of  the  variable  composition  of 
muscle-substance  we  give  the  following  summary,  chiefly  obtained 
from  K.  B.  Hofmann's  book.     The  figures  are  parts  per  1000. 

Muscles  from  Mammalia.  Birds.  Cold-blooded 

Solids 217-255  227-283  200 

Water 745-783  717-773  800 

Organic  bodies 208-245  217-263  180-190 

Inorganic  bodies 9-10  10-19  10-20 

Myosin   85-106  29.8-111  29.7-87 

Stroma  substance  (Danilewsky).  . . .  78-161  88.0-184  70.0-121 

Alkali  albuminate 29-30  —           -  — 

Crealin 2  3.4  2.3 

Xanthin  bodies 0.4-0.7  0.7-1.3  — 

Inosinic  acid  (barium  salt) 0.1  0.1-0.3  — 

Protic  acid —  —  7.0 

Taurin 0.7  (horse)  —  1.1 

Inosit 0.03  —  — 

Glycogen 4-5  -  —  3-5 

Lactic  acid 0.4-0.7  —  — 

Phosphoric  acid 3.4-4.8 

Potash 3.0-4.0 

Soda 0.4 

Lime 0.2 

Magnesia 0.4 

Sodium  chloride 0.04-0.1 

Iron  oxide 0.03-0.1 


MUSCLE.  271 

In  these  tables,  which  have  little  value  because  of  the  variation 
in  the  composition  of  the  muscles,  we  have  no  results  as  to  the 
estimates  of  fat.  Because  of  the  variable  quantity  of  fat  in  meat 
it  is  hardly  possible  to  quote  a. positive  average  for  this  body. 
After  most  careful  efforts  to  remove  the  fat  from  the  muscles  with- 
out chemical  means,  it  has  been  found  that  a  variable  amount  of 
inter-muscular  fat,  which  does  not  really  belong  to  the  muscular 
tissue,  always  remains.  The  smallest  quantity  of  fat  in  the  mus- 
cles from  lean  oxen  is,  according  to  Geouven,  6. 1  p.  m.,  and  accord- 
ing to  Peteesen,  7.6  p.  m.  This  last  observer  also  found  habitually 
a  smaller  amount  of  fat,  7.6-8.6  p.  m.,  in  the  fore  quarter  of  oxen, 
and  a  greater  amount,  30,1-34.6  p.  m.,  in  the  hind  quarter  of  the 
animal.  A  lower  amount  of  fat  has  also  been  found  in  the  muscles 
of  wild  animals.  B.  KoNiG  and  Faewick  found  in  the  muscles  of 
the  extremities  of  the  hare  10.7  p.  m.  fat,  and  14.3  p.  m.  in  the 
muscles  of  the  partridge.  The  muscles  of  pigs  and  fattened  ani- 
mals are,  when  all  the  appending  fat  is  removed,  very  rich  in  fat, 
amounting  to  40-90  p.  m.  The  muscles  of  certain  fishes  also  con- 
tain a  large  amount  of  fat.  According  to  x^lmei^,  the  flesh  of  the 
salmon,  mackerel,  and  eel  contain  respectively  100,  164,  and  329 
p.  m.  fat. 

The  quantity  of  watee  in  the  muscle  is  liable  to  considerable 
variation.  The  amount  of  fat  has  a  special  influence  on  the  quan- 
tity of  water,  and  we  find,  as  a  rule,  that  the  flesh  which  is  deficient 
in  water  is  correspondingly  rich  in  fat.  The  quantity  of  water 
does  not  depend  alone  upon  the  amount  of  fat,  but  upon  many 
other  circumstances,  among  which  we  must  mention  the  age  of  the 
animal.  In  young  animals  the  organs  in  general,  and  therefore 
also  the  muscles,  are  poorer  in  solids  and  richer  in  water.  In  man 
the  amount  of  water  decreases  until  mature  age,  but  increases  again 
towards  old  age.  Work  and  rest  also  influence  the  amount  of 
water,  for  the  active  muscle  contains  more  water  than  the  inactive. 
The  uninterruptedly  active  heart  should  therefore  be  the  muscle 
richest  in  water.  That  the  amount  of  water  may  vary  independ- 
ently of  the  amount  of  fat  is  strikingly  shown  by  comparing  the 
muscles  of  different  species  of  animals.  In  cold-blooded  animals 
the  muscles  generally  have  a  greater  amount  of  water,  in  birds  a 
lower.     The  comparison  of  the  flesh  of  cattle  and  fish  shows  very 


272  PHYSIOLOGICAL   CHEMISTRY. 

strikingly  the  different  amounts  of  water  (independent  of  the 
amount  of  fat)  in  the  flesh  of  different  animals.  According  to  the 
analyses  of  Almek,  the  muscles  of  lean  oxen  contain  15  p.  m.  fat 
and  767  p.  m.  water;  the  flesh  of  the  pike  contains  only  1.5  fat 
and  839  p.  m.  water. 

For  certain  purposes,  as,  for  example,  for  the  tests  of  the  exchange 
of  material,  it  is  important  to  know  the  amount  of  nitrogen  in  the 
flesh.  In  general,  it  may  be  considered  on  an  average  as  about  3.4^ 
of  the  fresh  lean  flesh  (Voit).  According  to  Nowak  and  Huppert 
this  quantity  may  vary  about  0.6^,  and  in  more  exact  investigations 
it  is  therefore  necessary  to  determine  the  nitrogen. 

Non-striated  Muscles. 

The  smooth  muscles  have  a  neutral  or  alkaline  reaction  (Du- 
Bois-Retmond)  when  at  rest.  During  activity  they  are  acid, 
which  is  inferred  from  the  observations  of  Bernsteijst,  who  found 
that  the  nearly  continually  contracting  sphincter  muscle  of  the 
Anodonta  is  acid  during  life.  The  smooth  muscles  may  also, 
according  to  HEiDENHAiif  and  Kuhnb,  pass  into  rigor  mortis  and 
thereby  become  acid.  Because  of  this  behavior  it  is  believed  that 
among  the  albuminous  bodies  of  the  smooth  muscles  there  is  also  a 
substance  forming  myosin.  A  spontaneously  coagulating  plasma 
has  not  thus  far  been  obtained,  but  it  may  be  considered  as  the  juice 
obtained  by  pressing  the  muscles  of  the  Anodonta  and  which 
coagulates  immediately  at  +  45°  0.  or  within  24  hours  at  the  ordinary 
temperature.  Myosin  has  not  been  found  in  the  smooth  muscles. 
Heidenhai]^"  and  Hellwig  have  obtained  from  the  smooth 
muscles  of  a  dog  an  albuminous  body  which  coagulates  at  -|-  45°- 
49°  C.  and  which  is  analogous  to  musculin.  The  smooth  muscles 
contain  large  amounts  of  alkali  albuminates  besides  an  albumin 
coagulating  at  +  75°  C. 

Hcemoglohin  occurs  in  the  smooth  muscles  of  certain  animals,  but 
is  absent  in  others.  Greatin  has  been  found  by  Lehmann.  Accord- 
ing to  Premt  and  Valenciennes,  the  muscles  of  the  Cepha- 
lopods  contain  taurvn  besides  creatinin  [creatinf).  Of  the  nou- 
nitrogenized  substances,  glycogen  and  lactic  acid  have  been  found 
without  doubt.  The  mineral  constituents  show  the  remarkable  fact 
that  the  sodium  combinations  exceed  the  potassium  combinations. 


CHAPTER  X. 
BRAIN  AND  NERVES. 

On  account  of  the  difl&culty  of  making  a  mechanical  separation 
and  isolation  of  the  different  tissue  elements  of  the  nervous  central 
organ  and  the  nerves,  we  must  resort  to  a  few  micro- chemical  re- 
actions, chiefly  to  qualitative  and  quantitative  investigations  of  the 
different  parts  of  the  brain,  in  order  to  study  the  different  chemical 
composition  of  the  cells  and  the  nerve-tubes.  The  chemical  investi- 
gation of  this  part  is  accompanied  with  the  greatest  difficulty ;  and 
although  our  knowledge  of  the  chemical  composition  of  the  brain 
and  nerves  has  been  somewhat  extended  by  the  investigations 
of  modern  times,  still  we  must  admit  that  this  chapter  is  yet  to-day 
one  of  the  most  obscure  and  complicated  in  physiological  chemistry. 

Albuminous  bodies  of  different  kinds  have  been  shown  to  be 
chemical  constituents  of  the  brain  and  nerves.  A  jDart  of  these  are 
insoluble  in  water  and  dilute  neutral-salt  solutions,  and  jjart  are 
soluble  therein.  Among  the  latter  we  find  albumin  and  globiilin. 
Nucleoalhumin,  which  is  often  considered  as  an  alkali  albuminate, 
also  occurs.  It  seems  unquestionable  that  the  albuminous  bodies 
belong  chiefly  to  the  gray  substance  of  the  brain  and  to  the  axis- 
cylinders.  The  same  remarks  apply  to  nudein  which  v.  Jaksch 
found  in  large  quantities  in  the  nerve  subtances.  NeuroTceratin 
(see  page  35),  which  was  first  detected  by  Ktjhne,  and  which  partly 
forms  the  neuroglia,  and  which  as  a  double  sheath  envelops  the 
outside  of  the  nerve  medulla  under  Schwann's  sheath  and  the 
inner  axis-cylinders,  chiefly  occurs  in  the  white  substance  (Kuhne 
and  Chittenden,  Baumstaek). 

The  phosphorized  substance  lyrotagon  must  be  considered  as  one 
of  the  chief  constituents,  perhaps  the  only  constituent  (Baum- 
stakk),  of  the  white  substance.      This  last-mentioned  substance 

273 


274  PHYSIOLOGICAL   CIIEMISTRT. 

yields  easily,  as  decomposition  products,  lecithin,  fatty  acids,  and  a 
nitrogenized  substance,  cerehrin;  this  last  probably  does  not  occur 
preformed  in  the  brain,  but  is  more  likely  a  product  of  transforma- 
tion (Baumstabk).  That  lecithin  also  is  pre-existent  in  the  brain 
and  nerves  can  hardly  be  doubted.  The  investigations  thus  far 
made  have  not  shown  decidedly  whether  it  is  more  abundant  in  the 
gray  or  white  substance.  Fatty  acids  and  neutral  fats  may  be 
prepared  from  the  brain  and  nerves;  but  as  these  may  be  readily 
derived  from  a  decomposition  of  lecithin  and  protagon,  which  exist 
in  the  fatty  tissue  between  the  nerve-tubes,  it  is  difficult  to  decide 
what  part  the  fatty  acids  and  neutral  fats  play  as  constituents  of 
the  real  nerve-substance.  Cholesterin  is  also  found  in  the  brain  and 
nerves,  a  part  free  and  a  part  in  chemical  combination  of  which  we 
know  nothing  about  (Baumstaek).  Cholesterin  seems  to  occur  in 
greater  abundance  in  the  white  substance.  Besides  these  substances 
the  nerve  tissue,  especially  the  white  substance,  contains  daubtless 
a  number  of  other  constituents  not  well  known,  and  among  which 
are  several  containing  phosphorus.  Thudichum  asserted  that  he 
had  isolated  a  number  of  phosphorized  substances  from  the  brain 
which  he  divided  into  three  principal  groups:  kepalines,  myelines, 
and  lecithines.  But  thus  far  this  assertion  has  not  been  confirmed 
by  other  investigators. 

By  allowing  water  to  act  on  the  contents  of  the  medulla,  round, 
or  long  double-contoured  drops  or  fibres,  not  unlike  double-con- 
toured nerves,  are  formed.  This  remarkable  formation,  which  can 
also  be  seen  in  the  medulla  of  the  dead  nerve,  has  been  called 
"  my eline  forfns,"  and  they  were  formerly  considered  as  produced 
from  a  special  body,  "  myeline."  Myeline  forms  may,  however,  be 
obtained  from  other  bodies,  such  as  protagon,  lecithin,  fat,  and  im- 
pure cholesterin,  and  they  depend  on  a  decomposition  of  the  con- 
stituents of  the  medulla,  chiefly  the  protagon. 

The  extractive  bodies  seem  to  be  almost  the  same  as  in  the  mus- 
cles. We  find :  creatin,  which  may,  however,  be  absent  (Baum- 
staek), xantliin  bodies,  inosit,  lactic  acid  (also  fermentation  lactic 
acid),  uric  acid,  jecorin  (according  to  Baldi,  in  the  human  brain), 
and  neuridin,  discovered  by  Brieger  and  which  is  most  interest- 
ing because  of  its  appearance  in  the  putrefaction  of  animal  tissues. 
Under  pathological  conditions  leucin  and  urea  have  been  found  in 


BRAIN  AND  NERVES.  275 

the  brain.  The  latter  is  also  a  physiological  constituent  of  the 
brain  of  cartilaginous  fishes. 

Of  the  above-mentioned  constituents  of  the  nerve-substance, 
protagon  and  its  decomposition  product,  cerebriu,  must  be  specially 
described. 

Protagon.  This  body,  which  was  discovered  by  Liebreich,  is  a 
nitrogenized  and  phosphorized  substance  whose  elementary  compo- 
sition, according  to  Gamgee  and  Blaxkexhorn,  is  C  66.39,  H 
10.69,  N  2.39,  and  P  1.06S  per  cent,  and  whose  empirical  formula  is 
CisoHsos^sPOjo.  On  boiling  with  baryta-water,  protagon  yields  the 
decomposition  products  of  lecithin,  namely,  fatty  acids,  glycero- 
phosphoric  acid,  and  cholin  (neurin?),  and  also  cerebrin.  On  boil- 
ing with  dilute  mineral  acids,  it  yields  among  other  products  a 
substance  which  is  Isevo-gyra te,  reducible,  and  fermentable. 

Protagon  appears,  when  dry,  as  a  white  loose  powder.  It  dis- 
solves in  alcohol  of  85  vols,  per  cent  at  -{-  Ab°  C,  but  separates  on 
cooling  as  a  snow-white,  flaky  precipitate,  consisting  of  balls  or 
groups  of  fine  crystalline  needles.  It  decomposes  on  heating  even 
below  100°  C.  It  is  hardly  soluble  in  cold  alcohol  or  ether,  but 
dissolves  on  warming.  It  swells  in  little  water,  decomposes  partly, 
and  gives  myaline  forms.  With  more  water  it  swells  to  a  gelatinous 
or  pasty  mass,  which  with  much  water  yields  an  opalescent  liquid. 
On  fusing  with  saltpetre  and  soda,  alkali  phosphates  are  obtained. 

Protagon  is  prepared  in  the  following  way  :  An  ox-brain  as 
fresh  as  possible,  with  the  blood  and  membranes  carefully  removed, 
is  ground  fine  and  then  extracted  for  several  hours  with  alcohol  of 
85  vols,  per  cent  at  +  45°  C,  filtered  at  the  same  temperature, 
and  the  residue  extracted  with  warm  alcohol  until  the  filtrate  does 
not  yield  a  precipitate  at  0°  C.  The  several  alcoholic  extracts  are 
cooled  to  0°  C,  and  the  precipitates  united  and  completely  extracted 
with  cold  ether,  which  dissolves  the  cholesterin  and  lecithin-like 
bodies.  The  residue  is  now  strongly  pressed  between  filter-paper 
and  allowed  to  dry  over  sulphuric  acid  or  phosphoric  anhydride. 
It  is  now  pulverized,  digested  with  alcohol  at  -f  45°  C,  filtered  and 
slowly  cooled  to  0°  C.  The  crystals  which  separate  may  be  purified 
when  necessary  by  recrystallization. 

The  same  steps  are  taken  when  we  wish  to  detect  the  presence 
of  protagon. 

Cerebrin.  Under  tiiis  name  W.  Muller  first  described  a  ni- 
trogenized substance,  free  from  phosphorus,  which  he  obtained  by 


276  PHYSIOLOGICAL  CHEMISTBT. 

extracting  a  brain-mass  whicli  had  been  previously  boiled  with 
baryta-water,  with  boiling  alcohol.  Following  a  method  essentially 
the  same,  but  differing  somewhat,  Geoghegan  prepared  from  the 
brain  a  cerebrin  with  the  same  properties  as  MiJLLER^s,  but  con- 
taining less  nitrogen.  According  to  Gamgee,  this  cerebrin  of 
Geoghegan  is  a  mixture  of  the  cerebrin  produced  by  the  decom- 
position of  the  protagon  and  a  substance  called  by  Gamgee  "  pseudo- 
cerebrin."  Furthermore,  Thudichum  has  collected  together  under 
the  name  "cerebrine^'  several  nitrogenized  bodies  free  from 
phosphorus,  such  as  Mtjller's  cerebrin  and  the  newer  bodies 
phrenosine  and  kerasene.  Lastly,  Parous  has  endeavored  to  prove 
that  the  cerebrin  described  by  both  Muller  and  Geoghegan  is  a 
mixture  of  three  bodies,  "cerebrin,"  *'homocerebrin,"  and  "  en- 
cephalin." 

From  the  above  statements  it  is  seen  that  the  composition  of  the  cerebrins 
is  still  unsettled,  so  that  we  cannot  admit  the  numerical  results  of  any  inves- 
tigator as  authoritative,  nor  can  we  even  take  an  average  as  correct,  and  we 
therefore  give  below  a  summary  of  the  results  thus  far  obtained  : 

C 

Milller's  cerebrin 68.45 

Geoghegan's  cerebrin 68.74 

Parcus's  cerebrin 69.08 

Parcus's  homocerebrin 70.06 

Parcus's  encephalin 68.40 

Gamgee's  pseudocerebrin 68.89 

Thudichum's  kerasene 68.90 

As  Geoghegan's  cerebrin  has  the  lowest  amount  of  nitrogen,  and  as  the 
analyses  of  this  investigator  agree  well  with  each  other,  it  is  ditficult  to  under- 
stand how  this  cerebrin  can  be,  as  Parous'  claims,  a  mixture  of  bodies 
richer  in  nitrogen  which  were  prepared  by  this  last-named  investigator.  On 
the  other  hand.  Parous  has  found  a  constant  composition  for  the  cerebrin 
irrespective  whether  it  was  recrystallized  two,  five,  or  eight  times,  and  it  is 
therefore  quite  as  unjustifiable  to  question  his  results.  Future  researches  are 
required  to  elucidate  this  question.  Gamgee's  pseudocerebrin  and  Thudi- 
chum's kerasene  have,  with  the  exception  of  the  amount  of  hydrogen,  so  sim- 
ilar a  composition  that  they  may  be  considered  as  identical. 

The  products  of  decomposition  of  the  cerebrins  possess  a  certain  interest. 
By  the  action  of  concentrated  sulphuric  acid  Geoghegan  obtained  a  Isevo- 
gyrate,  reducible  substance,  which  is  not  sugar  but  an  acid.  As  chief  product 
a  substance  is  obtained  which  he  called  "cetylid,"  C22H42O5 ,  and  which  on 
fusing  with  caustic  potash  yields  marsh-gas,  hydrogen,  and  palmitic  acid. 
According  to  him,  this  cetylid  is  probably  a  derivative  of  cetyl-alcohol. 

Of  special  interest  is  the  proof,  as  first  shown  by  Thudichum 
and  lately  substantiated  by  Thierfelder,  that  on  heating  the  so- 
called  cerebrin  with  dilute  sulphuric  acid  a   glucose  is  split  off. 


H 

N 

11.20 

4.50  per  cent 

10.91 

1.44   " 

11.47 

2.13   " 

11.60 

2.23   " 

11.60 

3.09   " 

11.87 

1.83   " 

11.36 

1.74   " 

BRAIN  AND  NERVES.  277 

This  glucose  is,  as  Thierfelder  has  proved,  identical  with  galac- 
tose. 

If  we  put  aside  the  above  differences  in  the  composition  and 
certain  somewhat  differing  statements  in  regard  to  the  qualitative 
reactions  of  cerebriij,  there  are  still  a  few  general  reactions  for  all 
cerebrin  preparations  which  may  be  employed  in  their  detection. 
From  these  lately-described  properties  it  has  been  claimed  that, 
besides  in  the  brain  and  nerves,  cerebrin  occurs  in  the  pus-cells, 
and  in  the  electric  organ  of  the  ray.  Geoghegan  has  also  found 
it  in  a  cancer  of  the  liver. 

Cerebrin,  as  generally  described,  is  in  the  dry  state  a  loose, 
purely  while,  odorless  and  tasteless  powder.  On  heating  it  becomes 
brown  at  about  80°  C,  puffs  up,  on  contiuuiug  the  heat  melts  and 
gradually  decomposes.  It  is  insoluble  in  water,  cold  alcohol,  or 
ether,  also  in  dilute  caustic  alkali  or  baryta-water.  It  swells  in 
boiling  water,  forming  a  pasty  mass.  It  dissolves  in  boiling  alcohol 
(also  ether),  but  on  cooling  aflocculent  precipitate  separates,  which 
on  microscopic  examination  is  found  to  consist  of  a  series  of  balls 
or  grains.  Cerebrin  is  chiefly  characterized  by  these  properties, 
and  by  its  yielding  a  reducible  substance  on  boiling  with  dilute 
mineral  acids. 

The  Parcus's  cerebrin  differs  from  the  ordinary  in  the  follow- 
ing particulars  :  it  is  not  soluble  in  boiling  ether ;  on  warming  it 
melts  without  decomposing  (which  takes  place  at  145°-160°  C);  it 
gives  a  light  yellow  solution  with  concentrated  sulphuric  acid,  and 
it  swells  very  little  in  cold  water. 

The  HOMOCEREBRiN  and  encephalin  of  Parous  remain  iu  the  mother 
liq\ior  after  the  precipitation  of  the  impure  cerebrin  from  the  alcohol.  These 
bodies  have  a  tendency  to  separate  as  gelatinous  mass.  Homocerebrin,  which, 
according  to  Parous,  is  homologous  to  cerebrin,  is  similar  to  it,  but  dissolves 
more  easily  in  warm  alcohol  and  also  in  warm  ether.  It  may  also  be  obtained 
as  extremely  fine  needles.  Encephalin  is  claimed  by  Parous  to  be  a  product 
of  the  metamorphosis  of  cerebrin.  In  the  perfectly  pure  state  it  crystallizes 
in  small  plates.  It  swells  in  warm  water,  forming  a  pasty  mass.  Like  the 
cerebrin  and  the  homocerebin,  it  yields  a  reducible  substance  on  boiling  with 
dilute  acids. 

Gamgee's  pseudooerebrin,  which  has  thus  far  not  been  closely  studied,  is 
obtained  as  a  by-product  in  the  recrystallization  of  protagon. 

The  cerebrins  are  generally  prepared  according  to  MtJLLER's 
method.  The  brain  is  first  stirred  with  baryta-water  until  it  ap- 
pears like  thin  milk,  and  then  it  is  boiled.     The  insoluble  parts 


278  PHYSIOLOGICAL   CHEMISTRY. 

are  removed,  pressed,  and  repeatedly  boiled  with  alcohol,  which  is 
filtered  while  boiling  hot.  The  impure  cerebrin  which  separates 
on  cooling  is  freed  from  cholesterin  and  fat  by  means  of  ether,  and 
then  purified  by  repeated  solution  in  warm  alcohol.  According 
to  Parous,  this  repeated  solution  in  alcohol  is  continued  until  no 
gelatinous  separation  of  homocerebrin  or  encephalin  takes  place. 

According  to  GEOGHEGAisr's  method,  the  brain  is  first  extracted 
with  cold  alcohol  and  ether  and  then  boiled  with  alcohol.  The 
precipitate  which  separates  on  the  cooling  of  the  alcoholic  filtrate 
is  treated  with  ether  and  then  boiled  with  baryta-water.  The  in- 
soluble residue  is  purified  by  repeated  solution  in  boiling  alcohol. 

The  cerebrin  may  also  be  obtained  from  other  organs  by  em- 
ploying the  above  methods.  The  quantitative  estimation,  when 
such  is  desired,  may  be  performed  in  the  same  way. 

Neuridin,  C5H14N2 ,  is  a  non-poisonous  dianiin  discovered  by  Brieger,  and 
which  was  obtained  by  him  in  the  putrefaction  of  meat  and  gelatine.  It 
also  occurs  imder  physiological  conditions  in  the  brain,  and  as  traces  in  the 
yolk  of  the  &gg. 

Neuridin  dissolves  in  water,  and  yields  on  boiling  with  alkalies  a  mixture  of 
diraethylamiu  and  trimethylamin.  It  dissolves  with  difficulty  in  amyl-alcohol. 
It  is  insoluble  in  ether  or  absolute  alcohol.  In  the  free  state  neuridin  has  a 
peculiar  odor,  suggesting  semen.  With  hydrochloric  acid  it  gives  a  combi- 
nation crystallizing  in  long  needles.  With  platinic  chloride  or  gold  chloride 
it  gives  crystallizable  double  combinations  which  are  valuable  in  its  prepara- 
tion and  detection. 

The  so-called  corptjscux,a  amylacea,  which  occur  on  the  upper  surface 
of  the  brain  and  in  the  pituitary  gland,  are  colored  more  or  less  pure  violet  by 
iodine  and  more  blue  by  sulphuric  acid  and  iodine.  They  consist,  perhaps, 
of  the  same  substance  as  certain  prostatic  calculi,  but  they  have  not  been 
closely  investigated. 

Quantitative  Composition  of  the  Brain.  The  quantity  of  water  is 
greater  in  the  gray  than  in  the  white  substance,  and  greater  in  new- 
born or  young  individuals  than  in  grown  ones.  The  brain  of  the 
foetus  contains  879-926  p.  m.  water.  According  to  the  observations 
of  Weisbach,  the  amount  of  water  in  the  several  parts  of  the  brain 
(and  in  the  medulla)  varies  at  different  ages.  The  following  fig- 
ures are  in  1000  parts  ;  A  for  men  and  B  for  women. 

20-30  Years. 
A.         B. 

White  substance  of 

the  brain 695.6  682.9 

Gray  ditto 833.6  826.2 

Gyri 784.7  792.0 

Cerebellum 788.3  794.9 

Ponsvaroli 784.6  740.3 

Medulla  oblongata  .  744.3  740.7 


30-50  Years. 

50-70  Years. 

70-94  Years, 

A. 

B. 

A. 

B. 

A. 

B. 

683  1 

703.1 

701.9 

689.6 

726.1 

722.0 

83(11 

8B0.6 

838.0 

838.4 

847.8 

889.5 

795.9 

772.9 

796.1 

796.9 

802.3 

801.7 

778.7 

789.0 

787.9 

784.5 

803.4 

797.9 

725  5 

722.0 

720.1 

714.0 

727.4 

724.4 

733.5 

729.8 

722.4 

730.6 

736.2 

736.7 

BRAIN  AND  NERVES.  279 

Quantitative  analyses  of  the  brain  have  also  been  made  by 
Petrowsky  on  an  ox-brain  and  by  Baumstark  on  the  brain  of  a 
horse.  In  the  analyses  of  Petrowsky  the  protagon  has  not  been 
considered,  and  all  organic,  phosphorized  substances  were  calcu- 
lated as  lecithin.  On  these  grounds  these  analyses  are  not  of  much 
value  from  a  certain  standpoint.  In  Baumstark's  analyses  the 
gray  and  the  white  substance  could  not  be  sufficiently  separated, 
and  these  analyses,  on  this  account,  show  partly  an  excess  of  white 
and  partly  an  excess  of  gray  substance  ;  nearly  one  half  of  the 
organic  bodies,  chiefly  consisting  of  bodies  soluble  in  ether,  could 
not  be  exactly  analyzed.  Neither  do  these  analyses  give  sufficient 
explanation  of  the  quantitative  composition  of  the  brain. 

The  analyses  made  up  to  the  present  time  give,  as  above  stated, 
an  equal  division  of  the  organic  constituents  in  the  gray  and  white 
substance.  In  the  analyses  of  Petrowsky  the  quantity  of  albumin 
and  gelatine-forming  substances  in  the  gray  matter  was  somewhat 
more  than  one  half,  and  in  the  white  about  one  quarter  of  the 
solid  organic  substances.  The  quantity  of  cholesterin  in  the  white 
was  about  one  half,  and  in  the  gray  substance  about  one  fifth,  of 
the  solid  bodies.  A  greater  quantity  of  soluble  salts  and  extractive 
bodies  was  found  in  the  gray  substance  than  in  the  white  (Baum- 
stark). The  following  analyses  of  Baumstark  give  the  most  im- 
portant known  constituents  of  the  brain  calculated  in  1000  parts 
of  the  fresh,  moist  brain.  A  represents  chiefly  the  white,  and  B 
chiefly  the  gray,  substance. 

A.  B. 

Water 695.35  769.97 

Solids 304.65  230.08 

Protagon 25.11  10.80 

lusoluble  albumin  and  connective  tissue 50.02  60.79 

Cholesterin,  free   18.19  6.30 

combined 26.96  17.51 

Nuclein 2.94  1.99 

Neurokeratin 18.93  10.48 

Mineral  bodies 5.23  5.62 

The  remainder  of  the  solids  probably  consists  chiefly  of  lecithin 
and  other  phosphorized  bodies.  Of  the  total  amount  of  phos- 
phorus, 15-20  p.  m.  belongs  to  the  nuclein,  50-60  p.  m.  to  the 
protagon,  150-160  p.  m.  to  the  ash,  and  770  p.  m.  to  the  lecithin 
and  the  other  phosphorized  organic  substances. 


280  PETSIOLOOICAL   CHEMISTRY. 

The  quantity  of  neurokeratin  in  the  nerves  and  in  the  different 
parts  of  the  brain  has  been  carefully  determined  by  Kuhne  and 
Chittenden".  They  found  3.16  p.  m.  in  the  plexus  brachialis, 
3.12  p.  m.  in  the  edge  of  the  cerebellum,  22.434  p.  m.  in  the  white 
substance  of  the  large  brain,  25.72-29.03  p.  m.  in  the  white  sub- 
stance of  the  corpus  callosum,  and  3.27  p.  m.  in  the  gray  substance 
of  the  edge  of  the  large  brain  (when  free  as  possible  from  white 
substance). 

The  quantity  of  mineral  constituents  in  the  brain  amounts  to 
2.95-7.08  p.  m.,  according  to  GtEOGHEGAN.  He  found  in  1000  parts 
of  the  fresh,  moist  brain  0.43-1.32  CI,  0,956-2.016  PO^,  0.244-0.796 
CO3 ,  0. 102-0.220  SOi ,  0. 01-0. 098  ^Q^{VOi)^ ,  0. 005-0.022  Ca,  0.016- 
0.072  Mg,  0.58  to  1.778  K,  0.450-1.114  Na.  The  gray  substance 
yields  an  alkaline  ash,  the  white  an  acid  ash. 

Appendix. 

The  Tissue  and  Fluids  of  the  Eye. 

The  retina  contains  in  all  816-880  p.  m.  water,  72-102  p.  m. 
proteid  bodies — myosin,  albumin,  and  mucin  (?),  9-32  p.  m.  lecithin, 
and  2.7-10.6  p.  m.  salts  (Hoppe-Seyler  and  Kahn").  The 
mineral  bodies  consist  of  420  p.  m.  Na2HP04  and  350  p.  m.  NaCl. 

Those  bodies  which  form  the  different  segments  of  the  rods 
have  not  been  closely  studied,  and  the  greatest  interest  is  therefore 
connected  with  the  coloring  matters  of  the  retina. 

Visual  purple,  also  called  rhodopsin,  erytJiropsin,  or  visual  red, 
is  the  pigment  of  the  rods.  Boll  observed  in  1876  that  the  layer 
of  rods  in  the  retina  during  life  had  a  purplish-red  color  which 
was  bleached  by  the  action  of  light.  Kuhne  showed  later  that  this 
red  color  might  remain  for  a  long  time  after  the  death  of  the  ani- 
mal if  the  eye  was  protected  from  daylight  or  investigated  by  a 
sodium  light.  By  these  conditions  it  was  also  possible  to  isolate 
and  closely  study  this  substance. 

Visual  red  (Boll)  or  visual  purple  (Kuhne)  has  become  known 
mainly  by  the  investigations  of  KiJHNE.  The  pigment  occurs 
chiefly  in  the  rods  and  only  in  their  outer  parts.  In  animals  whose 
retina  has  no  rods  the  visual  purple  is  absent,  and  is  also  necessarily 


BRAIN  AND  NERVES.  281 

absent  in  the  macula  lutea.  In  a  variety  of  bat  (rJiinoIopJms  hip- 
posideros),  in  hens,  pigeons,  and  new-born  rabbits,  no  visual  purple 
has  been  found  in  the  rods. 

A  solution  of  visual  purple  in  water  which  contains  2-5^ 
crystallized  bile,  the  best  solvent  for  it,  is  purple-red  in  color,  quite 
clear,  and  not  fluorescent.  On  evaporating  this  solution  in  vacuo,  we 
obtain  a  residue  similar  to  ammonium  carmiuate  which  contains 
violet  or  black  grains.  If  the  above  solution  is  dialyzed  with  water, 
the  bile  is  diffused  and  the  visual  purple  separates  as  a  violet  mass. 
Under  all  circumstances,  even  when  still  in  the  retina,  the  visual 
purple  is  quickly  bleached  by  direct  sunlight,  and  with  diffused 
light  with  a  rapidity  corresponding  to  the  intensity  of  the  light.  It 
passes  from  red  and  orange  to  yellow.  Eed  light  bleaches  the 
visual  purple  slowly;  the  ultra-red  light  does  not  bleach  it  at  all. 
A  solution  of  visual  purple  shows  no  special  absorption-bands,  but 
only  a  general  absorption  which  extends  from  the  red  side,  beginning 
at  D,  to  the  line  G.     The  strongest  absorption  is  found  at  £J. 

Visual  purple  when  heated  to  52°-53°  C.  is  destroyed  after  several 
hours,  and  almost  instantly  when  heated  to  +76°  0.  It  is  also 
destroyed  by  alkalies,  acids,  alcohol,  ether,  and  chloroform.  On  the 
contrary,  it  resists  the  action  of  ammonia  or  alum  solution. 

As  the  visual  purple  is  easily  destroyed  by  light,  it  must  there- 
fore also  be  regenerated  during  life.  Kuhne  has  also  found  that 
the  retina  of  the  eye  of  the  frog  becomes  bleached  when  exposed  for 
a  long  time  to  strong  sunlight,  and  that  its  color  gradually  returns 
when  the  animal  is  placed  in  the  dark.  This  regeneration  of  the 
visual  purple  is  a  function  of  tlie  liviug  cells  in  the  layer  of  the 
pigment  epithelium  of  the  retina.  This  may  be  inferred  from  the 
fact  that  a  detached  piece  of  the  retina  which  has  been  bleached 
by  light  may  have  its  visual  purple  restored  if  the  detached  piece 
of  the  retina  be  carefully  laid  on  the  chorioidea  having  layers  of  the 
pigment  epithelium  attached.  The  regeneration  has,  it  seems, 
nothing  to  do  with  the  dark  pigment,  the  melanin  or  fnscin,  in  the 
epithelium  cells.  A  partial  regeneration  seems,  according  to 
Ktjhne,  to  be  possible  in  the  completely-removed  retina.  On  ac- 
count of  this  property  of  the  visual  purple  of  being  bleached  by 
light  during  life,  we  may,  as  Kuhne  has  shown,  under  special  con- 
ditions and  by  observing  special  precautions,  obtain  after  death  by 


282  PHT8I0L0GIGAL   CHEMI8TRT. 

the  action  of  intense  light  or  more  continuous  light  the  picture  of 
bright  objects,  such  as  windows  and  the  like,  so-called  optograms. 

The  physiological  importance  of  visual  purple  is  unknown.  It 
follows  that  the  visual  purple  is  not  essential  to  sight,  since  it  is  ab- 
sent in  certain  animals  and  also  in  the  cones.  Holmgren  has 
further  shown  that  in  the  eye  of  a  frog  or  rabbit,  whose  retina 
has  been  previously  bleached  by  continuous  light,  a  flow  of  nega- 
tive electricity  is  continually  observed  in  the  optic  nerve  when  the 
eye  is  exposed  to  the  action  of  light. 

Visual  purple  must  always  be  prepared  exclusively  in  a  sodium 
light.  It  is  extracted  from  the  net  membrane  by  means  of  a 
watery  solution  of  crystallized  bile.  The  filtered  solution  is  evapo- 
rated in  vacuo  or  dialyzed  until  the  visual  purple  is  separated. 

The  pigments  of  the  cones.  In  the  inner  segments  of  the  cones  of  birds, 
reptiles,  and  fishes  a  small  fat-globule  of  varying  color  is  found.  Kuhne  has 
isolated  from  this  fat  a  green,  a  yellow,  and  a  red  pigment  called  respectively 
cMoropJian,  xanthopltan,  and  rhodophan. 

The  dark  pigment  of  the  epithelium  cells  of  the  net  membrane,  which 
was  formerly  called  melanin,  but  since  named  fusdn  by  Kuhne,  dissolves  in 
concentrated  caustic  alkalies  or  concentrated  sulphuric  acid  on  warming,  but, 
like  melanine  in  general  (see  Chapter  XIII),  has  been  little  studied.  The  pig- 
ment occurring  in  the  pigment-cells  of  the  chorioi'dea  seems  to  be  identical 
with  the  f  uscin  of  the  retina. 

The  vitreous  humor  is  often  considered  as  a  variety  of  gelatinous 
tissue.  It  contains  aZ^wmm  and,  as  C.  Th.  Moen^er  has  shown,  a 
mucoid  (see  page  234).  Among  the  extractives  we  find  a  little  urea 
— according  to  Picaed,  5.  p.  m.,  and  according  to  Rohmann",  0.64 
p.  m.  The  reaction  of  the  vitreous  humor  is  alkaline,  and  the 
quantity  of  solids  amounts  to  about  11  p.  m.  The  quantity  of 
mineral  bodies  is  about  9  p.  m.,  and  the  albuminous  bodies  0.7  p.  m. 
In  regard  to  the  aqueous  humor  see  page  126. 

The  crystalline  lens.  That  substance  which  forms  the  capsule 
of  the  lens  has  not  had  its  chemical  nature  closely  investigated, 
but  gives  a  reducible  body  when  boiled  with  dilute  acids 
(0.  Th.  Morner).  The  real  substance  of  the  lens,  the  lens-fibres, 
contains  as  chief  constituent  a  globulin  which  is  nearly  related  to 
vitellin  and  to  which  Berzelius  gave  the  name  crystallin.  This 
globulin  may  be  partially  precipitated  from  a  watery  extract  of  the 
lens  by  means  of  COg ,  and  it  may  be  completely  separated  by  satu- 
rating with  MgSO^.  The  statements  as  to  the  occurrence  of  an 
albumin  besides  the  globulin  in  the  lens  are  disputed;  that  at  least 


BRAIN  AND  NERVES.  283 

in  the  lens  of  cattle  an  albumin  occurs  is  nevertheless  easy  to  de- 
monstrate. 

A.  Bechamp  distinguishes  the  two  following  albuminous  bodies  in  the 
watery  extract  of  the  crystalline  lens.  Phacozymase,  which  coagulates  at 
+  55°  C,  contains  a  diastalic  enzyme  and  has  a  specific  rotary  power  of 
{a)j  —  —  41°,  and  the  crystalbumin,  with  a  specific  rotary  power  of 
(«j/=  —80.3°.  Bechamp  extracted  from  the  residue  of  the  lens,  which 
was  insoluble  in  water,  by  means  of  hydrocoloric  acid,  an  albuminous  body 
which  had  a  specific  rotary  power  of  {a)j  =  —  80.3°  which  he  called  crystal- 
fiOrin. 

The  lens  does  not  seem  to  contain  any  albuminous  body  which 
coagulates  spontaneously  like  fibrinogen.  That  cloudiness  which 
appears  after  death  depends,  according  to  Klthne,  upon  the  un- 
equal changing  of  the  concentration  of  the  contents  of  the  lens- 
tubes.  This  change  is  produced  by  the  altered  ratio  of  diffusion.  A 
cloudiness  of  the  lens  may  also  be  produced  in  life  by  a  rapid 
removal  of  water,  as,  for  example,  when  a  frog  is  plunged  into  a  salt 
or  sugar  solution  (Kunde).  The  appearance  of  cloudiness  in 
diabetes  has  been  attributed  by  some  to  the  removal  of  water. 
The  views  on  this  subject,  however,  do  not  accord. 

The  average  results  of  four  analyses  made  by  Laptschinskt  of 
the  lens  of  oxen  are  here  given,  calculated  in  parts  per  1000: 

Albuminous  bodies 349.3 

Lecithin 2.3 

Cholesterin 3.3 

Fat  3.9 

Soluble  salts 5.3 

Insoluble  salts 3.3 

In  cataract  the  amount  of  albumin  is  diminished  and  the  amount 
of  cholesterin  increased. 

The  corneal  tissue  has  been  previously  treated  of  (page  237). 
The  sclerotica  has  not  been  closely  investigated,  and  the  chlorioidea 
is  chiefly  of  interest  because  of  the  coloring  matter,  melanine,  it 
contains  (see  Chap.  XIII). 

Teaks  consist  of  a  water-clear,  alkaline  fluid  of  a  saltish  taste. 
According  to  the  analyses  of  Lerch,  they  contain  982  p.  m.  water, 
18  p.  m.  solids,  with  5  p.  m.  albumin  and  13  p.  m.  NaCl. 


284  PHYSIOLOGICAL   CHEMISTRY. 


The  Fluids  of  the  Inner  Ear. 

The  perilymph  and  endolymph  are  alkaline  fluids  which,  besides 
salts,  contain — in  the  same  amounts  as  in  transudations — traces  of 
albumin,  and  in  certain  animals  (torsk)  also  mucin.  The  quantity 
of  mucin  is  greater  in  the  perilymph  than  in  the  endolymph. 

Otoliths  contain  745-795  p.  m.  inorganic  substance  which  con- 
sists chiefly  of  crystallized  calcium  carbonate.  The  organic  sub- 
stance is  very  like  mucin. 


CHAPTEK  XI. 
ORGANS  OF  GENERATION. 

(a)  Male  Generative  Secretions. 

The  testes  have  teen  little  investigated  chemically.  We  find 
in  the  testes  of  animals  albuminous  bodies  of  different  kinds,  serum 
albumin,  alkali  albuminate  (?),  and  an  albuminous  body  related  to 
RoviDAs'  hyaline  substance,  also  leucin,  tyrosin,  creatin,  xanthiu 
bodies,  cholesterin,  lecithin,  inosit,  and/a^.  In  regard  to  the  occur- 
rence of  glycogen  the  statements  are  somewhat  contradictory. 
Daeeste  found  in  the  testes  of  birds  granules  similar  to  starch, 
which  were  colored  blue  with  difficulty  by  iodine. 

The  semen  as  ejected  is  a  white  or  whitish-yellow,  viscous, 
sticky  fluid  of  a  milky  appearance,  with  whitish,  non-transparent 
lumps.  The  milky  appearance  is  due  to  semen-fibres.  Semen  is 
heavier  than  water,  contains  albumin,  has  a  neutral  or  faintly- 
alkaline  reaction,  and  a  peculiar  specific  odor.  The  semen  of  bulls 
has  an  acid  reaction.  Soon  after  ejection  semen  becomes  gelati- 
nous, as  if  it  were  coagulated,  but  afterwards  becomes  more  fluid. 
When  diluted  with  water  white  flakes  or  shreds  separate  (Hexle's 
fibrin).  According  to  the  analyses  of  Vauquelin",  the  human 
semen  contains  900  p.  m.  water  and  100  p.  m.  solids,  with  60  p.  m. 
organic  and  40  p.  m.  inorganic  substance,  of  which  30  p.  m.  is  cal- 
cium phosphate.  Among  the  albuminous  bodies  Poster  claims 
that  propeptone  occurs  even  in  the  absence  of  the  semen-fibres. 

The  semen  in  the  vas  deferens  differs  chiefly  from  the  ejected 
in  that  it  is  without  the  peculiar  odor.  This  last  depends  on  the 
admixture  with  the  secretion  of  the  prostate.  This  secretion,  ac- 
cording to  Iyersen",  has  a  milky  appearance  and  ordinarily  an 
alkaline  reaction,  very  rarely  a  neutral  one,  contains  small  amounts 

285 


286  PHYSIOLOGICAL  GREMISTR7. 

of  proteids  and  mineral  bodies,  especially  NaCl.  Besides  these  it 
contains  a  crystalline  combination  of  phosphoric  acid  with  a  base, 
C2H5N.  This  combination  has  been  called  Bottchee's  siwrmine 
crystals,  and  it  is  claimed  that  the  specific  odor  of  the  semen  is  due 
to  a  partial  decomposition  of  these  crystals. 

The  crystals  which  appear  on  slowly-evaporating  the  semen, 
and  which  are  also  observed  in  anatomical  preparations  kept  in 
alcohol,  and  in  desiccated  egg-albumin,  are  identical,  according  to 
ScHREiNEE,  with  Chakcot's  Crystals  found  in  the  blood,  and  in 
the  lymphatic  glands  in  leucaemia.  They  are,  according  to  Schrei- 
2fEE,  a  combination  of  phosphoric  acid  with  a  base,  C2H5N,  which 
he  discovered,  and  this  base  is,  according  to  Ladenburg  and  Abel, 
probably  etliylenimin. 

The  semen-fibres  (spermatozoa)  show  a  great  resistance  to 
chemical  reagents  in  general.  They  do  not  dissolve  completely  in 
concentrated  sulphuric  acid,  nitric  acid,  acetic  acid,  nor  in  boiling- 
hot  soda  solutions.  They  are  dissolved  by  a  boiling-hot  caustic- 
potash  solution.  They  resist  putrefaction,  and  after  drying  they 
may  be  obtained  again  in  their  original  form  by  moistening  them 
with  a  Ifo  common-salt  solution.  By  careful  heating  and  burning 
to  an  ash  the  shape  of  the  spermatozoa  may  be  seen  in  the  ash.  The 
quantity  of  ash  is  about  50  p.  m.  and  consists  mainly  (|)  of  potas- 
sium phosphate. 

The  spermatozoa  show  well-known  movements,  but  the  cause 
of  this  is  not  known.  This  movement  may  continue  for  a  very  long 
time,  as  under  some  conditions  it  may  be  observed  for  several  days 
in  the  body  after  death,  and  in  the  secretion  of  the  uterus  longer 
than  a  week.  Acid  liquids  stop  these  movements  immediately;  they 
are  also  destroyed  by  strong  alkalies,  especially  ammoniacal  liquids, 
also  by  distilled  water,  alcohol,  ether,  etc.  The  movements  continue 
for  a  longer  time  in  faintly-alkaline  liquids,  especially  in  alkaline 
animal  secretions,  and  also  in  properly-diluted  neutral  salt-solutions. 

According  to  the  investigations  of  Mieschee,  there  are  lecithin 
and  niidein  but  no  cerebrin  in  the  spermatozoa  of  bulls.  The 
head  of  the  spermatozoa  contains  nuclein,  which  forms  probably 
the  outer  part  of  the  head;  albumin,  which  forms  the  contents  of 
the  head;  and  lastly  a  substance  rich  in  sulphur  which  has  not 
been  studied.     The  tail  dissolves  in  gastric  juice  after  contmuous 


ORGANS  OF  GENERATION.  287 

digestion,  uud  seems  to  consist  of  albuminous  bodies,  or  bodies 
closely  related,  which  show  a  variable  resistance  towards  pepsin- 
hydrochloric  acid.  The  semen  of  bulls  does  not  contain  any 
adenin,  but  the  other  three  xantliin  bodies  treated  of  on  pages 
49-51  (KossEL  and  Schindlee)  are  present. 

The  sPERiiATOZOA  of  the  Rhine  salmox  show,  according  to 
MiESCHER,  a  great  resistance.  With  caustic-potash  and  soda  solu- 
tions they  give  a  cloudy,  gelatinous  mass  which  is  precipitated  as 
shreds  by  acids  ;  but  these  shreds  do  not  dissolve  in  an  excess  of 
the  acid.  They  are  strongly  attacked  by  a  10-15^  solution  of 
XaCl  or  XaXOs,  and  the  semen  is  converted  by  such  a  solution 
into  a  stiff  gelatin.  The  head  is  attacked,  but  not  the  tail  or  the 
middle  part.  This  last-mentioned  part,  like  the  tail,  contains  albu- 
min, which  is  dissolved  by  hydrochloric  acid  of  1  p.  m.,  but  not  in 
XaCl.  MiESCHER  also  found  lecithin,  fat,  cliolesterin,  guanin,  and 
sarkin  in  relatively  large  amounts  in  tlie  salmon-semen.  The 
organic  constituent  occurring  in  the  largest  amount  in  the  salmon- 
semen  is,  according  to  Miescher,  a  combination  of  nuclein  with 
the  base  protamin,  C9H00X5O2.OH,  which  is  soluble  in  water  but 
insoluble  in  alcohol  or  ether. 

According  to  Miescher  and  Piccard,  the  spermatozoa  of  sal- 
mon contain  4ST  p.  m.  nuclein-protamin  (268  p.  m.  protamin), 
103  p.  m.  albuminous  bodies,  75  p.  m.  lecithin,  60-80  p.  m.  guanin 
and  sarkin,  22  p.  m.  cholesteriu,  and  45  p.  m.  fat.  Kossel  and 
ScHiNDLER  found  no  guanin,  but  xanthin  and  large  amounts  of 
adenin  and  hypoxauthin,  in  the  semex  of  the  carp. 

Spermatin  is  a  name  which  has  been  given  to  a  constituent  similar  to  alkali 
albuminate,  but  it  has  not  been  closely  studied. 

Prostatic  concrements  are  of  too  kinds.  One  is  verv  small,  generally  oval 
in  shape  -with  concentric  layers.  In  young  but  not  in  older  persons  they  are 
colored  blue  by  iodine  (Iversen).  According  to  Paulickt,  they  yield  sugar 
when  warmed  with  dilute  sulphuric  acid  ;  but  this  statement  has  not  been 
substantiated  by  I^tersen.  The  other  kind  is  larger,  sometimes  the  size  of 
the  head  of  a  pin,  and  consisting  chietiy  of  calcium  phosphate  (about  700 
p.  m.)  with  only  a  very  small  amount,  about  160  p,  m.,  organic  substance. 

(b)  Female  Generative  Organs. 

The  stroma  of  the  ovaries  are  of  little  interest  from  a  physio- 
logico-chemical  standpoint,  and  the  most  important  constituent  of 
the  ovaries,  the  Graafl&an  vesicles  with  the  ovum,  have  thus  far  not 


288  PHYSIOLOGICAL   CHEMI8TR7. 

been  the  subject  of  a  careful  chemical  investigation.  The  fluid  in 
the  vesicles  (of  the  cow)  do  not  contain,  as  has  been  stated,  the 
peculiar  bodies,  paralbumin  or  metalbumin,  which  are  found  in 
certain  pathological  ovarial  fluids,  but  seems  to  be  a  serous  liquid. 
The  corpora  lutea  are  colored  yellow  by  an  amorphous  coloring-mat- 
ter called  lutein.  Besides  this  another  coloring-matter  sometimes 
occurs  which  is  not  soluble  in  alkali  ;  it  is  crystalline,  but  not  iden- 
tical with  bilirubin  or  hsematoidin  ;  but  it  may  be  identified  as  a 
lutein  by  its  spectroscopic  behavior  (Piccolo  and  Lieben^,  Kuhn'e 
and  Ewald). 

The  cysts  often  occurring  in  the  ovaries  are  of  special  patho- 
logical interest,  and  these  may  have  essentially  different  contents, 
depending  upon  their  variety  and  origin. 

The  serous  cysts  (Hydrops  folliculorum  Geaapii),  which  are 
formed  by  a  dilation  of  the  Graafian  vesicles,  contain  a  serous 
liquid  which  has  a  specific  gravity  of  1.005-1.023.  A  specific 
gravity  of  1.020  is  less  frequent.  Generally  the  specific  gravity  is 
lower,  1.005-1.014,  with  10-40  p.  m.  solids.  As  far  as  is  known, 
the  contents  of  these  cysts  do  not  essentially  differ  from  other  serous 
liquids. 

The  proliferous  cysts  (myxoid  cysts,  colloid  cysts).  The 
contents  of  these  cysts  have  variable  properties. 

"We  sometimes  find  in  small  cysts  a  semi-solid,  transparent,  or 
somewhat  cloudy  or  opalescent  mass  which  appears  like  solidified 
glue  or  quivering  jelly  and  which  has  been  called  colloid  because  of 
its  physical  properties.  In  other  cases  the  cysts  contain  a  thick, 
tough  mass  which  can  be  drawn  out  into  long  threads,  and  as  this 
mass  in  the  different  cysts  is  more  or  less  diluted  with  serous 
liquids  their  contents  may  have  a  variable  consistency.  The  color 
of  the  contents  is  also  variable.  In  certain  cases  they  are  bluish 
white,  opalescent,  and  in  others  yellow,  yellowish  brown,  or  yellowish 
with  a  shade  of  green.  They  are  oiten  colored  more  or  less  choc- 
olate-brown or  red-brown,  due  to  the  decomposed  blood-coloring 
matters.  The  reaction  is  alkaline  or  nearly  neutral.  The  specific 
gravity,  which  may  vary  considerably,  is  generally  1.015-1.030,  but 
may  in  few  cases  be  1.005-1.010  or  1.050-1.055.  The  amount  of 
solids  is  variable.     In  rare  cases  they  amount  to  only  10-20  p.  m. ; 


ORGANS  OF  GENERATION.  289 

ordinarily  they  vary  between  50-70-100  p.  m.  In  a  few  cases 
150-200  p.  m.  solids  have  been  found. 

As  form-elements  we  find  red  and  coloiless  hlood-corpuscles, 
granular  cells,  partly  fat-degenerated  epithelium  and  partly  large 
so-called  Gluge's  coTY)nsc\es,  Jine  granular  masses,  epitlielium-cells, 
cliolesterin-crystals,  and  colloid  corpuscles — large,  circular,  refractive 
formations. 

Though  the  contents  of  the  proliferous  cyst  may  have  a  variable 
composition,  still  it  may  be  characterized  in  typical  cases  by  its 
slimy  or  ropy  consistency;  by  its  grayish-yellow,  chocolate-brown, 
sometimes  whitish-gray  color,  and  by  its  relatively  high  specific 
gravity,  1.015-1.025.  Such  a  liquid  does  not  ordinarily  show  a  spon- 
taneous fibrin-coagulation. 

TVe  consider  colloid,  metalbumin  a,nd  paralbumin  as  character- 
istic constituents  of  these  liquids. 

Colloid.  This  name  does  not  designate  any  particular  chemical 
substance,  but  is  given  to  the  contents  of  tumors  with  certain 
physical  properties  similar  to  gelatinous  glue.  Colloid  is  found 
as  a  diseased  product  in  several  organ?. 

Colloid  is  a  gelatinous  mass,  insoluble  in  water  and  acetic  acid; 
it  is  dissolved  by  alkalies  and  gives  a  liquid  which  is  not  precipi- 
tated by  acetic  acid  or  by  acetic  acid  and  potassium  ferrocyanide. 
Sometimes  a  colloid  is  found  which,  when  treated  with  a  very 
dilute  alkali,  gives  a  solution  similar  to  a  mucin  solution.  On 
boiling  with  acids  colloid  gives  a  reducible  substance.  It  is  related 
to  mucin,  and  it  is  considered  by  certain  investigators  as  a  trans- 
formed mucin.  A  colloid  found  by  Wurtz  in  the  lungs  contains 
C  48.09,  H  7.47,  N  7.00,  and  0  37.44^.  Colloids  of  different  origin 
seem  to  have  an  unequal  composition. 

Metalbumin.  This  name  Scherer  gave  to  a  proteid  substance 
found  by  him  in  an  ovarial  fluid.  The  metalbumin  was  considered 
by  Scherer  to  be  an  albuminous  body,  but  it  belongs  to  the  mucin 
group  and  it  is  therefore  called  by  the  author  pseudornucin. 

Pseudomucin.  This  body,  which,  like  mucin,  gives  a  reducible 
substance  when  boiled  with  acids,  is  a  mucoid  of  the  following 
composition:  C49.75,  H6.98,  NlO.28,  SL25,  0  31.74^  (author). 
"With  water  pseudomucin  gives  a  slimy,  ropy  solution,  and  it  is  this 
substance  which  gives  the  fluid  contents  of  the  ovarial  cysts  their 


290  PHTSIOLOQICAL   CHEMISTRY. 

typical  ropy  property.  Its  solutions  do  not  coagulate  on  boiling 
but  only  become  milky-opalescent.  Unlike  mucin  solutions, 
pseudomucin  solutions  are  not  precipitated  by  acetic  acid.  With 
alcohol  they  give  a  coarse  flocculent  or  thready  precipitate  which 
only  dissolves  in  water  or  alcohol  after  having  been  kept  in  these 
liquids  for  a  long  time. 

Paralbumin  is  another  substance  discovered  by  Schekee  and 
which  occurs  in  ovarial  liquids  and  also  in  ascites  fluids  with  the 
simultaneous  presence  of  ovarial  cysts  and  rupture  of  the  same.  It 
is  therefore  only  a  mixture  of  pseudomucin  with  variable  amounts 
of  albumin,  and  the  reactions  of  paralbumin  are  correspondingly 
variable. 

The  detection  of  metalbamin  and  paralbumin  is  naturally  con- 
nected with  the  detection  of  pseudomucin.  A  typical  ovarial  fluid 
containing  pseudomucin  is,  as  a  rule,  sufficiently  characterized 
by  its  physical  properties,  and  a  special  chemical  investiga- 
tion is  only  necessary  in  cases  where  a  serous  fluid  contains  very 
small  amounts  of  pseudomucin.  We  proceed  in  the  following  way: 
The  albumin  is  removed  by  heating  to  boiling  with  the  addition 
of  acetic  acid;  the  filtrate  is  strongly  concentrated  and  precipitated 
by  alcohol.  The  precipitate  is  carefully  washed  with  alcohol 
and  then  dissolved  in  water.  A  part  of  this  solution  is  digested 
with  saliva  at  the  temperature  of  the  body  and  then  tested  for  glu- 
cose (derived  from  glycogen  or  dextrin).  If  glycogen  is  present,  it 
will  be  converted  into  glucose  by  the  saliva;  precipitate  again  with 
alcohol  and  then  proceed  as  in  the  absence  of  glycogen.  In  this 
last-mentioned  case,  first  add  acetic  acid  to  the  solution  of  the 
alcohol  precipitate  in  water  so  as  to  precipitate  any  existing  mucin. 
The  precipitate  produced  is  filtered,  the  filtrate  treated  with  2fo 
HCl  and  warmed  on  the  water-bath  until  the  liquid  is  deep  brown 
in  color.  In  the  presence  of  pseudomucin  this  solution  gives 
Trommer's  test. 

The  other  proteid  bodies  which  have  been  found  in  cystic 
fluids  are  serum-globulin  and  serum-albumin,  peptone  (?),  mucin, 
and  mucin-peptone  (?).  Fibrin  only  occurs  in  exceptional  cases. 
The  quantity  of  mineral  bodies  on  an  average  amount  to  about 
10  p.  m.  The  amount  of  extractive  bodies  (cJiolesterin  and  urea) 
and  fat  is  ordinarily  2-4  p.  m.  The  remaining  solids,  which  con- 
stitute the  chief  mass,  are  albuminous  bodies  and  pseudomucin. 

The  intraligamentary,  papillary  cysts  contain  a  yellow,  yellowish- 


OHGANS  OF  GENERATION.  291 

green,  or  brownish-green  liquid  which  either  contains  no  pseudo- 
mucin  or — witli  the  simultaneous  degeneration  of  colloid — very 
little.  The  specific  gravity  is  generally  rather  high,  1.032-1.036  with 
90-100  p.  m.  solids.  The  principal  constituents  are  the  albuminous 
bodies  of  blood-serum. 

The  rare  tubo-ovarial  cysts  contain  as  a  rule  a  watery,  serous 
fluid  containing  no  pseudomucin. 

The  parovarial  cysts  or  the  cysts  of  the  ligamenta  lata  may 
attain  a  considerable  size.  In  general  the  contents  are  watery, 
mostly  very  pale  yellow-colered,  water-clear  or  only  slightly  opales- 
cent liquids.  The  specific  gravity  is  low,  1.002-1.009  ;  and  the 
solids  only  amount  to  10-20  p.  m.  Pseudomucin  does  not  occur  as 
a  typical  constituent  ;  albumin  is  sometimes  absent,  and  when  it 
does  occur  the  quantity  is  very  small.  The  principal  part  of  the 
solids  consist  of  salts  and  extractive  bodies.  In  exceptional  cases 
the  fluid  may  be  rich  in  albumin,  and  may  show  a  higher  specific 
gravity. 


The  Egg. 

The  small  ova  of  man  and  mammalia  cannot,  for  evident  rea- 
sons, be  the  subject  of  a  searching  chemical  investigation.  Up  to 
the  present  time  the  eggs  of  birds,  amphibians,  and  fishes  have  been 
investigated,  but  above  all  the  hen's  egg.  We  will  here  occupy 
ourselves  with  the  constituents  of  this  last. 

The  yolk  of  the  hen's  egg.  In  the  so-called  white  yolk,  which 
forms  the  germ  with  a  continuation  reaching  to  the  centre  of  the 
yolk  ilatebra)  and  also  a  layer  found  between  the  yolk  and  yolk- 
membrane,  we  find  albumin,  nuclein,  lecWim,  and  potassium 
(Liebermann).  The  occurrence  of  glycogen  is  doubtful.  The 
yolk-membrane  consists  of  an  albumoid  similar  in  certain  respects 
to  keratin  (Liebermann). 

The  principal  part  of  the  yolk — the  nutritive  yolk  or  yellow — is 
a  viscous,  non-transparent,  pale-  or  orange-yellow  alkaline  emulsion 
of  a  mild  taste.  The  yolk  contains  vitellin,  lecithin,  cliolesterin, 
fat,  coloring  matters,  traces  of  neuridin  (Brieger),  glucose  in  very 
small  quantities,  and  mineral  hodies.     The  occurrence  of  cerebrin 


292  PHYSIOLOGICAL   CEEMllSTBT. 

and  of  granules  similar  to  starch  (Dareste)  has  not  been  positively 
proved. 

Ovovitellin.  This  body  is  generally  considered  as  a  globulin, 
but  it  resembles  a  nucleoalbumin  more.  The  question  as  to  what 
relationship  other  proteid  substances,  such  as  the  aleurone  crystals 
of  certain  semen,  and  the  so-called  "  dotterpldttchen  "  in  the  eggs 
of  certain  fishes  and  amphibians  which  are  related  to  ovovitellni, 
bear  to  this  substance,  is  a  question  which  requires  further  investi- 
gation. 

The  ovovitellin  which  has  been  prepared  from  the  yolk  of  eggs 
is  not  a  pure  albuminous  body,  but  always  contains  lecithin. 
Hoppe-Seyler  found  25^  lecithin  in  vitellin  and  also  some  nuclein. 
The  lecithin  may  be  removed  by  boiling  alcohol,  but  the  vitellin 
is  changed  thereby  and  it  is  therefore  probable  that  the  lecithin  is 
chemically  united  with  the  vitellin  (Hoppe-Seyler).  Bunge 
prepared  a  nuclein  by  digesting  the  yolk  with  gastric  juice,  and  this 
nuclein,  according  to  him,  is  of  great  importance  in  the  formation 
of  the  blood,  and  on  these  grounds  he  called  it  Jmmatogen.  This 
hsematogen — whose  composition  is  as  follows:  0  42.11,  H  6.08,  N 
14.73,  S  0.55,  P  5.19,  Fe  0.29  and  0  31.05^  seems  to  be  a  product 
of  the  decomposition  of  vitellin. 

Vitellin  is  similar  to  the  globulins  in  that  it  is  insoluble  in 
water  ;  but  on  the  contrary  soluble  in  dilute  neutral-salt  solutions 
(although  the  solution  is  not  quite  transparent).  It  is  also  soluble 
in  hydrochloric  acid  of  1  p.  m.  and  in  very  dilute  solutions  of  alka- 
lies or  alkali  carbonates.  It  is  precipitated  from  its  salt  solution 
by  diluting  with  water,  and  when  allowed  to  stand  some  time  iu 
contact  with  water  the  vitellin  is  gradually  changed,  forming  a  sub- 
stance more  like  the  albuminates.  The  coagulation  temperature 
for  the  solution  containing  salt  (NaCl)  lies  between  -)-  70°  and  75°  0. 
or,  when  heated  very  rapidly,  at  about  +  80°  C.  Vitellin  differs 
from  the  globulins  in  yielding  nuclein  by  pepsin  digestion.  On 
this  account  vitellin,  as  previously  stated  (page  14),  is  considered  as 
a  nucleoalbumin  even  though  it  differs  from  them  in  general  by 
the  coagulation  of  its  neutral  solutions  containing  salt,  at  a  tem- 
perature below  100°  0. ;  also  by  certain  solubilities  and  precipita- 
tions. Because  of  the  difficulty  of  removing  lecithin  without 
changing  the  properties  of  vitellin  it  is  necessary,  since  lecithin  may 


ORGANS  OF  OENERATION.  293 

essentially  change  the  solubility  and  precipitating  capacity  of  the 
albuminous  body,  to  wait  for  further  investigations  before  we  place 
vitellin  definitely  in  the  globulin  or  nucleoalbumin  group. 

The  chief  points  in  the  preparation  of  ovovitellin  are  as  follows: 
The  yolk  is  thoroughly  agitated  with  ether;  the  residue  is  dissolved 
in  a  10^  common-salt  solution,  filtered,  and  the  vitellin  precipitated 
by  adding  an  abundance  of  water.  The  vitellin  is  now  purified  by 
repeatedly  redissolving  in  dilute  common-salt  solutions  and  precipi- 
tating by  water. 

The  yolk  also  contains,  besides  vitellin,  alkali-alhuminate  and 
albumin. 

The/«^  of  the  yolk  of  the  egg  is,  according  to  LiEBERMANiif,  a 
mixture  of  a  solid  and  a  liquid  fat.  The  solid  fat  consists  cluefly  of 
tripalmitin  with  some  stearin.  On  the  saponification  of  the  egg-oil 
LiEBERMANN"  obtained  40^  oleic  acid,  38.04^  palmitic  acid  and 
15.21^  stearic  acid.  The  fat  of  the  yolk  of  the  egg  contains  less 
carbon  than  other  fats,  which  may  depend  on  the  presence  of 
mono  and  diglycerides  or  on  a  quantity  of  fatty  acid  deficient  in 
carbon  (Liebermann). 

Lutein.  Yellow  or  orange-red  amorphous  coloring  matters 
occur  in  the  yellow  of  the  egg  and  in  several  other  places  in  the 
animal  organism,  for  instance  in  the  blood-serum  and  serous  fluids, 
fatty  tissues,  milk-fat,  corpora  hitea,  and  in  the  fat-globules  of  the 
retina.  These  coloring  matters,  which  also  occur  in  the  vegetable 
kingdom  (Thudichum),  have  been  called  luteines  or  lijjochromes. 

The  luteines,  which  among  themselves  show  somewhat  different 

properties,  are  all  soluble  in  alcohol,  ether,  and  chloroform.     They 

differ  from  the  bile-coloring  matter,  bilirubin,  in  that  they  are  not 

separated  from  their  solution  in  chloroform  by  water  containing 

alkali,  and  also  in  that  they  do  not  give  the  characteristic  play  of 

colors  with  nitric  acid  containing  a  little  nitrous  acid,  but  give  a 

transient  blue  color,  and  lastly  they  give  an  absorption-spectrum  of 

ordinarily  two  bands,  of  which  one  covers  the  line  F  and  the  other 

lies  between  the  lines  F  and  G.     The  luteines  withstand  the  action 

of  alkalies  so  that  they  are   not  changed    when  we   remove  the 

fats  present  by  means  of  saponification. 

The  lutein  from  tlie  yolk  of  the  Qgg  has  not  been  prepared  in  a  pure  state. 
According  to  Chevreul  and  Gobley,  the  yolk  contains  a  partly  red  and  part- 
ly yellow  pigment.     Maly  has  found  two  pigments  free  from  iron  in  the  eggs 


294  PHTSIOLOQICAL  CHEMISTRY. 

of  the  water-spider  {maja  squinado),  one  a  red,  vitelloruhin,  and  the  other  a  yel- 
low pigment,  mtdlolutem.  Both  of  these  pigments  are  colored  blue  by  nitric 
acid  containing  nitrous  acid,  and  beautifully  green  by  concentrated  sulphuric 
acid.  The  absorption-bands,  especially  of  the  vitellolutein,  correspond  very 
nearly  with  those  of  ovolutein. 

The  mineral  bodies  of  the  yolk  of  the  egg  consist,  according  to 
PoLECK,  of  51.2-65.7  parts  soda,  89.3-80.5  potash,  122.1-132.8 
lime,  20.7-21.1  magnesia,  14.5-11.90  iron  oxide,  638.1-667.0  phos- 
phoric acid,  and  5.5-14.0  parts  silicic  acid  in  1000  parts  of  the  ash. 
We  find  phosphoric  acid  and  lime  the  most  abundant,  and  then 
potash,  which  is  somewhat  greater  in  quantity  than  the  soda.  These 
results  are  not,  however,  quite  correct,  first,  because  no  dissolved 
phosphate  occurs  in  the  yolk  (Liebermann),  and  secondly,  in 
burning,  phosphoric  and  sulphuric  acids  are  produced  and  these 
drive  away  the  chlorine,  which  is  not  accounted  for  in  the  pre- 
ceding analyses. 

The  yolk  of  the  hen's  egg  weighs  about  12-18  grms.  The 
quantity  of  water  and  solids  amounts,  according  to  Parkes,  to 
471.9  p.  m.  and  528.1  p;  m.  respectively.  Among  the  solids  ho 
found  156.3  p.  m.  albumin,  3.53  p.  m.  soluble  and  6.12  p.  m.  in- 
soluble salts.  The  quantity  of  fat,  according  to  Parkes,  is  228.4 
p.  m.,  the  lecithin,  calculated  from  the  amount  of  phosphorus  in 
the  organic  substance  in  the  alcohol-ether  extract,  was  107.2  p.  m., 
and  the  cholesterin  17.5  p.  m. 

The  white  of  the  Qg^  is  a  faint-yellowish  albuminous  fluid  en- 
closed in  a  framework  of  thin  membranes  ;  and  this  fluid  is  in  it- 
self very  liquid,  but  seems  viscous  because  of  the  presence  of  these 
fine  membranes.  That  substance  which  forms  the  membranes, 
and  of  which  the  chalaza  consists,  seems  to  be  a  body  nearly 
related  to  horn  substances  (Liebermanf). 

The  white  of  the  egg  has  a  specific  gravity  of  1.045  and  always 

nas  an  alkaline  reaction.     It  contains  850-880  p.  m.  water,  100-130 

p.  m.  albuminous  bodies,  and  7  p.  m.  salts.     Among  the  extractive 

bodies   Lehmann   found   a    fermentable    hind   of   sugar   which 

amounted  to  5  p.  m.,  or  according  to  Meissner,  80  p.  m.     Besides 

these,  we  find  in  the  white  of  the  egg  traces  of  fats,  soaps,  lecithin, 

and  cholesterin. 

Tlie  white  of  the  earg  during  incubation  becomes  transparent  on  boiling 
and  acts  in  many  respects  like  alkali-albuminate.  This  albumin  Tarchanoff 
called  "  tatalbumin." 


OUGANS  OF  GEAEBATION.  295 

The  albuminous  bodies  of  the  white  of  the  egg  belong  partly  to 
the  globulin  and  partly  to  the  albumin  group. 

The  egg-globuUn  is,  according  to  Dillner,  closely  related  to 
serum-globulin.  On  diluting  the  white  of  the  egg  with  water  it 
partly  separates.  It  is  also  precipitated  by  magnesium  sulphate. 
The  quantity  of  globulins  in  the  white  of  the  egg  is  on  an  average 
6. 67  p.  m.,  or  about  6T  p.  m.  of  the  total  proteids.  According  to 
CoRix  and  Berakd,  we  have  two  globulins  in  the  white  of  the 
egg,  one  coagulating  at  -f  57.5°  C,  and  the  other  at  -|-  67°  G. 

Ovalbumin,  or  the  albumin  of  the  white  of  the  egg.  The  com- 
position of  this  albumin  is  C  52.35,  H  6.9,  N  15.25,  and  S  1.93^. 
The  ovalbumin  has  the  properties  of  the  albumins  in  general,  but 
differs  from  serum-albumin  in  the  following  :  The  specific  rotary 
power  is  lower  oc{D)  =  —  38°.  Solutions  containing  medium 
amounts  of  the  albumin  coagulate  at  +  56°  C,  irrespective  whether 
the  amount  of  salt  present  is  large  or  small.  On  the  contrary,  the 
temperature  of  coagulation  changes  with  a  constant  amount  of  salt, 
but  with  variable  amounts  of  albumin  in  the  solution.  Ovalbumin 
is  quickly  rendered  insoluble  by  alcohol.  It  is  precipitated  by  a 
sufficient  quantity  of  nitric  or  hydrochloric  acid,  but  it  dissolves 
with  more  difficulty  in  an  excess  of  these  acids  than  the  serum -al- 
bumin. Ovalbumin  in  solution,  when  introduced  into  the  blood- 
circulation,  passes  into  the  urine,  which  is  not  the  case  with  serum- 
albumin. 

According  to  Gautier  and  Bechamp,  ovalbumin  is  a  mixture  of  two 
albumins  with  a  coagulation  temperature  60"-63^  and  71°-74"  C.  respectively. 
According  to  CoRix^  and  Berakd,  it  is  a  mixture  of  three  albumins  with  a 
coagulation-temperature  respectively  67",  73°,  and  82°  C.  Perhaps  the  fact 
has"  been  overlooked  that  the  coagulation -temperature  of  ovalbumin  is 
changed  by  variable  amounts  of  albumin  in  solution. 

Ovalbumin  is  obtained  by  precipitating  the  globulins  with 
MgSOt  at  -j-  20°  C.  and  saturating  the  filtrate  with  NaaSO^  at  the 
same  temperature.  The  ovalbumin  which  separates  is  filtered, 
pressed,  dissolved  in  water,  and  freed  from  salts  by  dialysis.  The 
dialyzed  solution  is  then  evaporated  in  a  vacuum  or  at  40°-50°  C. 
If  precipitated  with  alcohol,  albumin  becomes  quickly  insoluble. 

The  mineral  bodies  of  the  white  of  the  egg  have  been  analyzed 
by  PoLECK  and  Weber.  They  found  in  1000  parts  of  the  ash : 
276.6-284.5  grms.  potash,  235.6-329.3  soda,  17.4-29  lime,  16-31.7 


296  PHYSIOLOGICAL   CHEMISTRY. 

magnesia,  4.4-5.5  iron  oxide,  238.4-285.6  chlorine,  31.6-48.3  phos- 
phoric acid  (P2O5),  13.2-26.3  sulphuric  acid,  3.8-20.4  silicic  acid 
and  96.7-116  grms.  carbon  dioxide.  Traces  of  fluorine  have  also 
been  found  (Nickles).  The  ash  of  the  white  of  the  egg  contains, 
as  compared  with  the  yolii,  a  greater  amount  of  chlorine  and  alka- 
lies, and  a  smaller  amount  of  lime,  phosphoric  acid,  and  iron. 

The  Shell-membrane  and  the  Egg-shell.  The  shell-membrane 
consists,  as  above  stated  (page  35),  of  a  keratin  substance.  The 
shell  contains  very  little  organic  substance,  36-65  p.  m.  The 
chief  mass,  more  than  900  p.  m.,  consists  of  calcium  carbonate; 
besides  this  there  are  very  small  amounts  of  magnesium  carbon- 
ate and  earthy  jjhosphates. 

The  different  coloring  of  birds'  eggs  depends,  as  Wicke,  Sokby,  liiEBER- 
MANN  and  Krukenberg  have  shown,  upon  several  coloring  matters.  Among 
these  we  find  a  red  or  reddish-brown  pigment  called  "  oorodein"  by  Sorby, 
which  is  perhaps  identical  with  hsematoporphyrin  (Sorby,  Krukenberg). 
The  green  or  blue  coloring  matter,  Sorby's  oocyan,  seems,  according  to 
LiEBERMANN,  and  Krukenberg,  to  be  partly  biliverdin  and  partly  a  blue 
derivative  of  the   bile-pigments. 

The  eggs  of  birds  have  a  space  at  their  blunt  end  filled  with 
gas ;  this  gas  contains  on  an  average  23.3  vols,  per  cent  oxygen 
(Bischoff). 

The  weight  of  a  hen's  egg  varies  between  40-60  grammes  and 
may  weigh  sometimes  70  grms.  The  shell  and  shell-membrane  to- 
gether when  carefully  cleaned,  but  still  in  the  moist  state,  weigh 
5-8  grms.  The  yolk  weighs  12-18  and  the  white  23-34,  or  about 
double. 

The  white  of  the  egg  of  cartilaginous  and  bone  fishes  contains  only  traces 
of  true  albumin,  and  the  cover  of  the  frog's  egg  consists,  according  to  Giacosa, 
of  mucin.  The  crystalline  formations  {yolk-spherules  or  dotterplditcJien)  which 
have  been  observed  in  the  Qgg  of  the  tortoise,  frog,  ray,  shark,  and  other 
fishes,  and  which  are  described  by  Valenciennes  and  Fremy  under  the 
names,  emydin,  ichthin,  iddhidin,  and  ichihulin,  contain  lecithin,  nuclein,  and 
albumin.  They  probably  correspond  to  the  yellow  yolk-globule  in  the  nutri- 
tive yolk  of  the  hen's  egg.  The  egg  of  the  river  crab  and  the  lobster  contain 
the  same  pigment  as  the  shell  of  the  animal.  This  pigment,  called  cyano- 
crysiallin,  becomes  red  on  boiling  in  water. 

In  fossil  eggs  (of  aptenodytes,  pelecanus,  and  hali.«:us)  in  old  guano 
deposits  a  yellowish-white,  silky,  lamiated  combination,  has  been  found 
which  is  called  guanovulit,  (NH4)2S04  +  2K2SO4  -f  3KHSO4  +  4H2O,  and 
which  is  easily  soluble  in  water  but  is  insoluble  in  alcohol  and  ether. 

Those  eggs  which  develop  outside  of  the  mother-organism  must 
contain  all  the  elements  necessary  for   the  young  animals.      One 


OUGANS  OF  GENERATION.  297 

finds,  therefore,  in  the  yolk  and  white  of  the  egg  an  abundant  quan- 
tity of  albuminous  bodies  of  different  kinds,  and  especially  a  phos- 
phorized  albumin  in  the  yolk.  Further,  we  also  find  lecithin  in  the 
yolk,  which  seems  to  habitually  occur  in  the  developing  cell.  The 
occurrence  of  glycogen  is  doubtful,  and  the  carbohydrates,  which 
have  no  direct  value  as  tissue-builders,  are  perhaps  represented  by  a 
very  small  amount  of  glucose.  On  the  contrary,  the  egg  contains 
a  large  proportion  of  fat,  which  doubtless  is  an  important  source  of 
nutrition  and  respiration  for  the  embryo.  The  cholesterin  and  the 
lutein  can  hardly  have  a  direct  influence  on  the  development  of  the 
embryo.  The  egg  also  seems  to  contain  the  mineral  bodies  neces- 
sary for  the  development  of  the  young  animal.  The  lack  of  phos- 
phoric acid  is  compensated  by  an  abundant  amount  of  phosphorized 
organic  substance,  and  the  nucleoalbumin  containing  iron,  from 
which  the  hgematogen  (see  page  292)  is  formed,  is  doubtless,  as 
BuNGE  claims,  of  great  importance  in  the  formation  of  the  haemo- 
globin containing  iron.  The  silicic  acid  necessary  for  the  develop- 
ment of  the  feathers  is  also  found  in  the  egg. 

During  the  period  of  incubation  the  egg  loses  weight,  chiefly  due 
to  loss  of  water.  The  quantity  of  solids,  especially  the  fat  and  the 
albumins,  diminishes  and  the  egg  gives  off  not  only  carbon  dioxide, 
but  also,  as  Liebermann  has  shown,  nitrogen  or  a  nitrogenized 
substance.  This  loss  is  compensated  by  the  absorption  of  oxygen, 
and  it  is  found  that  during  incubation  a  respiratory  exchange  of 
gas  takes  place.  While  the  quantity  of  dry  substance  in  the  egg 
during  this  period  always  decreases,  the  quantity  of  mineral  bodies, 
albumin,  and  fat  always  increases  in  the  embryo.  The  increase  in 
the  amount  of  fat  in  the  embryo  depends,  according  to  Lieber- 
MANN,  in  great  part  upon  a  taking  up  of  the  nutritive  yolk  in  the 
abdominal  cavity.  The  weight  of  the  shell  and  the  quantity  of  lime 
salts  contained  therein  remains  unchanged  during  incubation.  The 
yolk  and  white  together  contain  the  necessary  quantity  of  lime  for 
development. 

The  mo5t  complete  and  careful  chemical  investigation  on  the 
development  of  the  embryo  of  the  hen  has  been  made  by  Libber- 
MANN.  From  his  researches  we  may  quote  the  following:  In  the 
earlier  stages  of  the  development,  tissues  very  rich  in  water  are 
formed,  but  on  the  continuation  of  the  development  the  quantity  of 


298  PHYSIOLOGICAL   CHEMISTRY. 

water  decreases.  The  absolute  quantity  of  bodies  soluble  in  water 
increases  with  the  development,  while  their  relative  quantities,  as 
compared  to  the  other  solids,  continually  decreases.  The  quantity 
of  bodies  soluble  in  alcohol  quickly  increases.  A  specially  impor- 
tant increase  is  noticed  in  the  fat,  whose  quantity  is  not  very  great 
even  on  the  fourteenth  day,  but  after  that  it  becomes  considerable. 
The  quantity  of  albuminous  bodies  and  albuminoid  insoluble  in  water 
grows  continually  and  regularly  in  such  a  way  that  their  absolute 
quantity  increases  while  their  relative  quantity  remains  nearly  un- 
changed. LiEBERMAiSTK  found  no  glutin  in  the  embryo  of  the  hen. 
The  embryo  does  not  contain  any  gelatin-forming  substance  until 
the  tenth  day,  and  from  the  fourteenth  day  on  it  contains  a  body 
which  when  boiled  with  water  gives  a  substance  similar  to  chondrin. 
A  body  similar  to  mucin  occurs  in  the  embryo  when  about  six  days 
old,  but  then  disappears.  The  quantity  of  hemoglobin  shows  a 
continual  increase  compared  to  the  weight  of  the  body.  Lieber- 
MANisr. found  that  the  relationship  of  the  hasmoglobin  to  the  bodily 
weight  was  1:  728  on  the  eleventh  day  and  1:  421  on  the  twenty- 
first  day. 

The  tissue  of  the  placenta  has  not  thus  far  been  the  subject  of  detailed 
chemical  investigations.  In  the  edges  of  the  placenta  of  bitches  and  of  cats  a 
ciystallizable  orange- colored  pigment  (bilirubin  ?)  has  been  found,  and  also  a 
green  amorphous  pigment,  Meckel's  Jwinatochlorin,  which  is  considered  as 
biliverdin  by  Etti.  Pketer  questions  the  identity  of  these  pigments  with 
biliverdin. 

From  the  cotyledons  of  the  placenta  in  ruminants  a  white  or  faint  rose- 
colored  creamy  fluid,  lYie  uterine  milk,  can  be  obtained  by  pressure.  It  is  al 
kaline  in  reaction,  but  becomes  acid  quickly.  Its  specific  gravity  is  1.033- 
1.040.  It  contains  as  form-elements  fat-globules,  small  granules,  and  epithe- 
lium-cells. We  have  found  81.3-120.9  p.  m.  solids,  61.2-105.6  p.  m.  albumin, 
about  10  p.  m.  fat,  and  3.7-8.2  p.  m.  ash  in  the  uterine  milk. 

The  fluid  occurring  in  the  so-called  gkape-mole  {')nola  racemosa)  has  a 
low  specific  gravity,  1.009-1.012,  and  19.4-26.3  p.  m.  solids  with  9-10  p.  m. 
protein  bodies  and  6-7  p.  m.  ash. 

The  amniotic  fluid  is  in  women  thin,  whitish,  or  pale  yellow; 
sometimes  it  is  somewhat  yellowish  brown  and  cloudy.  White 
flakes  separate.  The  form-elements  are  mucus-corpuscles,  epitlie- 
lium-cells,  fat-droin,  and  lanugo  hair.  The  odor  is  stale,  the  reaction 
neutral  or  faintly  alkaline.     The  specific  gravity  is  1.002-1.028. 

The  amniotic  fluid  contains  the  constituents  of  ordinary  transu- 
dations. The  amount  of  solids  at  birth  is  hardly  20  p.  m.  In  the 
earlier  stages  of  pregnancy  the  fluid  contains  more  solids,  especially 


ORGANS  OF  GENERATION.  299 

proteids.  Among  the  albuminous  bodies  "Wetl  found  one  sub- 
stance similar  to  vitellin  and  with  great  probability  also  serum 
albumin,  besides  small  quantities  of  mucin.  Glucose  is  regularly 
found  in  the  amniotic  fluid  of  cows,  but  not  in  human  beings.  On 
the  contrary,  the  human  amniotic  fluid  contains  some  urea  and 
allantoin.  The  quantity  of  these  may  be  increased  in  hydramnion 
(Prochownick,  Harnack),  which  depends  on  an  increased  secre- 
tion by  the  kidneys  and  skin  of  the  foetus.  Creatin  and  lactates 
are  questionable  constituents  of  the  amniotic  fluid.  The  quantity 
of  urea  in  the  amniotic  fluid  is,  according  to  Prochowxick,  0.16 
p.  m.  In  the  fluid  in  hydramnion  Prochownick  and  Harn^ack 
found  respectively  0.34  and  0.48  p.  m.  urea.  The  chief  mass  of 
the  solids  consists  of  salts.  The  quantity  of  chlorides  (NaCl)  is 
5.7-6.6  p.  m. 


300  PHTSIOLOGIGAL  CHEMISTRY. 


CHAPTER  XII. 

MILK. 

The  chemical  constituents  of  the  mammary  glands  have  beeii 
little  studied.  The  protoplasm  of  the  cells  is  rich  in  proteids  and, 
as  is  generally  admitted,  consists  in  great  part  of  casein  or  a  sub- 
stance nearly  related.  If  all  the  milk  is  removed  from  the  mam- 
mary gland  by  thorough  washing,  the  cells  still  contain  a  large 
quantity  of  proteids  which  swell  up  to  a  slimy,  ropy,  or  fibrous 
mass  when  very  dilute  alkali  (1-2  p.  m.  KOH)  is  added.  These 
proteids  consists  mainly  of  nucleoalbumin,  which  is  gradually 
changed  by  the  action  of  the  alkali.  If  the  mammary  gland  is 
boiled  with  water,  the  protoplasm  of  the  cell  is  decomposed  and  a 
nucleoalbumin  passes  into  solution,  which  may  be  precipitated  by 
the  addition  of  acetic  acid,  and  which  is  characterized  by  its  greater 
insolubility  in  acetic  acid,  compared  with  casein.  This  nucleo- 
albumiu,  which  may.  well  be  considered  as  a  protoplasm-nucleo- 
albumin  changed  by  heat,  also  gives  on  boiling  with  dilute  mineral 
acids  a  reducible  substance  whose  nature  is  not  known.  The 
relation  the  above-mentioned  nucleoalbumin,  which  is  more  cor- 
rectly designated  as  a  proteid  when  the  mother-substance  of  the 
reducible  body  does  not  occur  as  an  impurity,  bears  to  the  sugar  of 
milk  or  the  mother-substance  of  the  same,  has  not  been  determined. 
According  to  Beet,  the  secreting  glands  contain  a  body  which  on 
boiling  with  dilute  mineral  acids  yields  a  reducible  substance. 
Such  a  substance,  which  acts  as  a  step  towards  the  formation  of 
milk-sugar,  has  also  been  observed  by  Thieefelder.  Fat  seems 
to  be  a  never-failing  constituent  of  the  cell,  at  least  in  the  secreting 
gland,  and  this  fat  may  be  observed  in  the  protoplasm  as  large  or 
small  globules  similar  to  milk-globules.     The  extractive  bodies  of 


MILK.  301 

the  mammary  glands  have  been  little  investigated,  but  among  them 
we  find  considerable  amounts  of  xanthin  bodjes. 

As  human  milk  and  milk  of  animals  are  essentially  of  the  same 
constitution,  it  seems  best  to  speak  first  of  the  one  most  thoroughly 
investigated,  namely,  cow's  milk,  and  then  of  the  essential  proper- 
ties of  the  remaining  important  varieties  of  milk. 

Cow's  Milk. 

Cow's  milk  forms,  as  all  milks  do,  an  emulsion  which  consists 
of  very  finely-divided  fat  suspended  in  a  solution  consisting  chiefly 
of  albuminous  bodies,  milk-sugar,  and  salts.  Milk  is  non-trans- 
parent, white,  whitish  yellow,  or  in  thin  layers  somewhat  bluish 
white,  of  a  faint,  insipid  odor  and  mild,  faintly-sweetish  taste.  The 
reaction  is  regularly  amphoteric,  sometimes  with  a  stronger  action 
on  the  red  and  sometimes  on  the  blue  litmus-paper.  The  specific 
gravity  is  1.028  to  1.0345  at  +  15°  C. 

Milk  gradually  changes  when  exposed  to  the  air,  and  its  reaction 
becomes  more  acid.  This  depends  on  a  transformation  of  the 
milk-sugar  into  lactic  acid,  which  is  produced  partly  by  the  pres- 
ence of  a  special  enzyme  originating  in  the  glands  but  not  yet 
positively  detected,  but  which  is  chiefly  produced  by  micro- 
organisms. 

Entirely  fresh,  amphoteric  milk  does  not  coagulate  on  boiling, 
but  forms  a  skin  consisting  of  coagulated  casein  and  lime-salts, 
which  rapidly  re-forms  after  being  removed.  Even  after  passing  a 
current  of  carbon  dioxide  through  the  fresh  milk  it  does  not  coagu- 
late on  boiling.  In  proportion  as  the  formation  of  lactic  acid  ad- 
vances this  behavior  changes,  and  soon  a  stage  is  reached  when  the 
milk,  which  has  previously  had  carbon  dioxide  passed  through  it, 
coagulates  on  boiling.  At  a  second  stage  it  coagulates  alone  on 
heating ;  then  it  coagulates  by  passing  carbon  dioxide  alone  with- 
out boiling;  and  lastly,  when  the  formation  of  lactic  acid  is  suffi- 
cient, it  coagulates  spontaneously  at  the  ordinary  temperature, 
forming  a  solid  mass.  It  may  also  happen,  especially  in  the  warmth, 
that  the  casein-clot  contracts  and  a  yellowish  or  yellowish-green 
acid  liquid  (acid  whey)  is  separated. 

If  the  milk  is  sterilized  bv  heating  and  contact  with  micro- 


302  PHYSIOLOGICAL   CHEMISTRY. 

organisms  prevented,  the  formation  of  lactic  acid  may  be  entirely 
stopped.  The  formation  of  acid  may  also  be  prevented,  at  least  for 
some  time,  by  many  antiseptics,  such  as  salicylic  acid  (1:5000), 
thymol,  boracic  acid,  and  other  laodies. 

If  milk  is  allowed  to  stand  for  a  long  time  at  a  temperature  of  0°  C.  it  re- 
mains fluid  for  several  weeks,  but  coagulates  at  last.  In  this  case  the  coagula- 
tion is  not  caused  by  the  formation  of  lactic  acid,  but  is  more  likely  due  to 
the  formation  of  fatty  acids  caused  by  an  oxidation  (HopPE-SEYiiER). 

If  freshly-milked  amphoteric  milk  is  treated  with  rennet,  it 

coagulates  quickly,  especially  at  the  temperature  of  the  body,  to  a 

solid  mass  (cheese),  from  which  a  yellowish  fluid  (sweet  whey)  is 

gradually  pressed  out.     This  coagulation  of  milk  occurs  without 

any  change  in  its  reaction  ;  it  may  also  take  place  with  the  very 

faintest  alkaline  reaction;   therefore  it  is  distinct  from  the  acid 

coagulation. 

Milk  sometimes  undergoes  a  peculiar  kind  of  coagulation,  being  converted 
into  a  thick,  ropy,  slimy  mass  (thick  milk).  This  conversion  depends,  accord- 
ing to  ScHMiDT-MuLHEiM,  upou  a  peculiar  change  of  the  milk-sugar  in  which 
this  last  is  converted  into  a  slimy  product.  This  conversion  is  caused  by  a 
special  organized  ferment. 

In  cow's  milk  we  find  as  form-elements  a  few  colostrum  cor- 
puscles (see  Colostrum)  and  a  few  pale  nucleated  cells.  The 
number  of  these  form-elements  is  very  small  compared  with  the 
immense  amount  of  the  most  essential  form-constituents,  the  milk- 
globules. 

The  Milk-globules.  These  consist  of  extremely  small  drops  of 
fat  whose  number  is,  according  to  Bohr,  2.6-11.4  or  an  average  of 
5.6  million  in  1  c.  mm.  and  whose  diameter  is  0.00014-0.0063 
mm.  (Bohr).  It  is  unquestionable  that  milk-globules  contain  fat, 
and  we  consider  it  as  positive  that  all  the  milk-fat  is  found  in 
them.  Another  and  disputed  question  is  whether  milk-globules 
consist  entirely  of  fat  or  whether  they  also  contain  albumin. 

According  to  an  observation  of  Ascherson,  the  drops  of  fat  are 
covered  with  a  fine  albuminous  coat,  a  so-called  haptogen-memhrane, 
when  placed  in  an  alkaline  albumin  solution.  As  miljs:  on  shaking 
with  ether  does  not  give  up  its  fat,  or  only  very  slowly  by  a  great 
excess  of  ether,  and  as  this  takes  place  very  easily  after  the  addition 
of  acids  or  alkalies  which  dissolve  albumin,  it  was  formerly  thought 
that  the  fat-globules  of  the  milk  were  enveloped  in  an  albuminous 


MILK.  303 

coat.  A  true  membrane  has  not  been  detected;  and  since,  when 
no  means  of  dissolving  the  albumin  is  resorted  to — for  example, 
when  the  milk  is  precipitated  by  carbon  dioxide  after  the  addition 
of  very  little  acetic  acid  (Soxhlet),  or  when  it  is  coagulated  by 
rennet — the  fat  can  be  very  easily  extracted  by  ether,  the  theory  of  a 
special  albuminous  membrane  for  the  fat-globules  has  been  gener- 
ally abandoned.  The  observations  of  Quinckes  on  the  behavior 
of  the  fat-globules  in  an  emulsion  prepared  with  gum  have  led, 
at  the  present  time,  to  the  conclusion  that  each  fat -globule  in  the 
milk  is  surrounded  by  a  stratum  of  casein  solution  by  means  of 
molecular  attraction,  and  this  prevents  the  globules  from  uniting 
with  each  other.  Everything  that  changes  the  physical  property 
of  the  casein  in  the  milk  or  precipitates  it  must  necessarily  help 
the  solution  of  the  fat  in  ether,  and  it  is  in  this  way  that  the  alka- 
lies, acids,  and  rennet  work.^ 

If  we  accept  this  view,  which  requires  further  proof,  we  must  not  over- 
look the  fact  that  the  fat-globules  remain  unchanged  when  the  milk  under 
agitation  is  coagulated  with  rennet.  In  this  case  we  find  an  immense  amount 
of  unchanged  milk-globules  in  the  whey,  and  if  we  wish  to  admit  of  a  stratum 
of  proteids  around  the  fat-globules  proceeding  from  the  molecular  attraction, 
we  must  not  consider  that  it  is  entirely  due  to  casein,  but  also  to  albumin. 

If  the  fat-globules  are  filtered  off  and  washed  ou  a  filter,  we  always  obtain 
(Radenhausen  and  Danilewsky)  after  their  treatment  with  ether  a  residue 
consisting  of  albumin.  From  this  behavior  the  deduction  has  been  made  that 
the  fat-globules,  even  though  they  have  no  real  membrane,  consist,  neverthe- 
less, of  fat  and  albumin.  The  extreme  difficulty  of  completely  removing  the 
albuminous  bodies  of  the  milk  by  washing  the  fat  on  the  filter  renders  it 
necessary  to  exercise  great  caution  in  drawing  a  conclusion.  The  question  as 
to  the  composition  of  the  milk-globules,  and  especially  as  to  the  possible 
amount  of  albumin,  cannot  be  decided  at  present. 

The  milk-fat  has  a  rather  variable  specific  gravity,  which  accord- 
ing to  BoHK,  is  0.949-0.996  at  -  15°  C.  The  milk-fat,  which  is  ob- 
tained under  the  name  of  butter,  consists  in  great  part  of  the 
neutral  fats  pahnitin,  olem,  and  steai'm.  Besides  these  it  contains, 
as  triglycerides,  small  quantities  of  butyric  acid  and  caproic  acid, 
traces  of  caprylic  and  cafric  acids  (lauric  acid  probably  also  occurs), 
myristic  and  arachidic  acids.  Butter  which  has  been  exposed 
to  the  action  of  sunlight  contains  also  formic  acid  (Duclaux). 
Milk-fat  also  contains  a  small  quantity  of  lecithin  and  cliolesterin, 
also  a  yellow  coloring  matter.  The  quantity  of  volatile  faiity  acids 
in  butter  is,  according  to  Duclaux,  on  an  average  about  70  p.  m,, 
of  which  37-51  p.  m.  is  butyric  acid  and  20-33  p.  m.  is  caproic 


304  PHYSIOLOGICAL   CHEMISTRY. 

acid.     The  non-volatile  fat  consists  of  yV  to  ^V  ol^in,  and  the  re- 
mainder of  a  mixture  of  palmitin  and  stearin. 

The  quantity  of  volatile  fatty  acids  in  butter-fat  is  of  great  practical  im- 
portance in  the  methods  for  detecting  the  presence  of  foreign  fats  in  butter. 
This  detection  is  performed  generally  according  to  Reichekt's  process  based 
on  Hehner  and  Angell's  method.  The  fat  is  saponitied  with  alcoholic 
potash  and  the  alcohol  evaporated.  The  soaps  are  dissolved  in  water,  and  then 
distilled  with  an  excess  of  phosphoric  acid.  The  quantity  of  volatile  fatty 
acids  in  the  distillate  is  determined  by  titration  with  deci-normal  alkali.  With 
butter  of  proper  composition  2.5  grms.  should  yield  a  distillate  requiring 
14-18  cc.  for  neutralization,  and  at  least  not  less  than  13  cc.  of  the  deci-normal 
alkali.  In  proportion  as  the  butter  contains  a  greater  quantity  of  foreign  fats 
the  quantity  of  alkali  required  becomes  smaller. 

The  milk-plasma,  or  that  fluid  in  which  the  fat-globules  are  sus- 
pended, contains  at  least  three  different  albuminous  bodies,  casein, 
lactoglohulin,  and  ladalhumin,  and  two  carbohydrates,  of  which  only 
one,  the  milk-sugar,  is  of  great  importance.  The  milk-plasma  also 
contains  extractive  bodies,  traces  of  uHa,  creatin,  creatinin,  hypo- 
xanthin  {?),  lecitlmi,  cliolesterin,  about  1  p.  m.  citric  acid  (Soxhlet 
and  Henkel)  ;  a  still  greater  amount  according  to  Soldner,  and 
lastly  also  mineral  bodies  and  gases. 

Casein.  This  protein  substance,  which  thus  far  has  been  de- 
tected positively  in  milk,  belongs  to  the  nucleoalbumins,  and  differs 
from  the  albuminates  by  its  containing  phosphorus  and  by  its  be- 
havior with  the  rennet  enzyme.  Casein  from  cow's  milk  has  the 
following  composition:  C  53.0,  H  7.0,  N  15.7,  S  0.8,  P  0.85,  and 
0  22.65  per  cent.  Its  specific  rotation  is,  according  to  Hoppe- 
Seyler  somewhat  variable  ;  in  neutral  solution  it  is  a{D)  =  —  80°. 
The  question  whether  the  casein  from  different  varieties  of  milk  is 
identical  or  if  there  are  several  different  caseins  has  not  been  posi- 
tively determined. 

Casein,  when  dry,  appears  like  a  fine  white  powder  which,  after 
heating  to  100°  C.  or  somewhat  above,  shows  the  properties  and 
solubilities  of  freshly-precipitated,  still-moist  casein.  Casein  is  only 
slightly  soluble  in  water  or  in  neutral-salt  solutions.  It  acts  Tike  a 
rather  strong  acid,  dissolves  readily  in  water  on  the  addition  of  very 
little  alkali,  forming  a  neutral  or  acid  liquid,  and  lastly  it  dissolves 
in  water  in  the  presence  of  calcium  carbonate,  from  which  it  expels 
the  carbon  dioxide.  If  casein  is  dissolved  in  lime-water  and  this 
solution  treated  with  very  dilute  phosphoric  acid  until  it  is  neutral 


MILK.  305 

in  reaction,  the  casein  appears  to  remain  in  solution,  but  is  prob- 
ably only  swollen  as  in  milk,  and  the  liquid  contains  at  the  same 
time  a  large  quantity  of  calcium  phosphate  without  any  precipitate 
or  any  visible  suspended  particles.  The  casein  solutions  cohtaining 
lime  are  opalescent  and  have  on  warming  the  appearance  of  milk 
deficient  in  fat.  Therefore  it  is  not  impossible  that  the  white 
color  of  the  milk  is  due  partly  to  the  casein  and  calcium  phosphate. 

Casein  solutions  do  not  coagulate  on  boiling,  but  are  covered,  as 
milk,  with  a  skin.  It  is  precipitated  by  very  little  acid,  but  the 
presence  of  neutral  salts  retards  the  precipitation.  A  casein  solu- 
tion containing  salt,  or  ordinary  milk,  requires,  therefore,  more  acid 
for  precipitation  than  a  salt-free  solution  of  casein  of  the  same  con- 
centration. The  precipitated  casein  dissolves  very  easily  again  in  a 
small  excess  of  the  acid,  but  less  easily  in  an  excess  of  acetic  acid. 
The  acid  solutions  are  precipitated  by  mineral  acids  in  excess. 
Casein  is  precipitated  from  neutral  solutions  or  from  milk  by 
common  salt  or  magnesium  sulphate  in  substance  without  changing 
its  properties.  Metallic  salts,  such  as  copper  sulphate,  completely 
precipitate  the  casein  from  neutral  solutions. 

The  property  which  is  the  most  characteristic  of  casein  is  that  it 
coagulates  with  rennet  in  the  presence  of  a  sufficiently  great  amount 
of  lime-salts.  In  solutions  free  from  lime-salts  the  casein  does  not 
coagulate.  According  to  Soxhlet  and  Soldnee,  the  soluble  lime- 
salts  are  only  of  essential  importance  in  coagulation,  while  the  cal- 
cium phosphate  is  without  importance.  The  chemical  processes 
which  take  place  in  the  rennet  coagulation  have  not  been  thorough- 
ly investigated  ;  still  several  observations  seem  to  show  that  casein 
splits  partly  into  a  difficultly  soluble  body  paracasein  or  cheese^ 
whose  composition  closely  resembles  that  of  casein  and  which  forms: 
the  chief  product,  and  partly  into  an  easily-soluble  substance, 
similar  to  albumose,  loliey -albumin,  which  is  deficient  in  carbon  and 
nitrogen  (50.3^  C  and  13.2^  N,  Kostner)  and  which  is  produced 
in  very  small  quantities.  Paracasein  is  not  further  changed  by  the 
rennet  enzyme,  and  it  has  not  the  same  property  of  holding  calcium 
phosphate  in  solution  as  casein  has.  If  rennet  be  added  to  a  casein 
solution  free  from  lime,  the  solution  does  not  coagulate,  but  the 
casein  is  changed  so  that  the  solution,  after  the  enzyme  has  been 
destroyed  by  rapid  heatiug,  acts  like  a  paracasein  solution,  on  the 


306  PHYSIOLOGICAL   CHEMISTRY. 

addition  of  lime-salts  after  cooling.  The  action  of  the  rennet 
enzyme  on  casein  takes  place  also  in  the  absence  of  lime-salts,  and 
these  last  are  only  necessary  for  the  coagulation  or  the  precipitation 
of  the  paracasein. 

Casein  may  be  prepared  in  the  following  way  :  The  milk  is  di- 
luted with  4  vols,  water  and  the  mixture  treated  with  acetic  acid  to 
0.75  to  1  p.  m.  Casein  thus  obtained  is  purified  by  repeated  solu- 
tions in  water  with  the  aid  of  the  smallest  quantity  of  alkali  pos- 
sible, by  filtrating  and  reprecipitating  with  acetic  acid,  and 
thoroughly  washing  with  water.  Most  of  the  milk-fat  is  retained 
by  the  filter  on  the  first  filtration,  and  the  casein  contaminated  with 
traces  of  fat  is  purified  by  treating  with  alcohol  and  ether. 

Lacto globulin  was  obtained  by  Sebelief  from  cow's  milk  by 
saturating  it  with  NaCl  in  substance  (which  precipitated  the 
casein),  and  saturating  the  filtrate  with  magnesium  sulphate.  As 
far  as  it  has  been  investigated  it  had  the  properties  of  serum-glob- 
ulin, with  which  it  is  perhaps  identical. 

Lactalbumin  was  first  prepared  in  a  pure  state  from  milk  by 
Sebelien.  Its  composition  is,  according  to  Sebelien,  C  52.19, 
H  7.18,  N  15.77,  S  1.73,  0  23.13  per  cent.  Lactalbumin  has  the 
properties  of  the  albumins.  It  coagulates,  according  to  the  con- 
centration and  the  amount  of  salt  in  solution,  at  -\-  72°  to  84°  C. 
It  is  similar  to  serum  albumin,  but  differs  from  it  in  having  a  con- 
siderably lower  specific  rotary  power;  a  {D)  =  —  37°. 

The  principle  of  the  preparation  of  lactalbumin  is  the  same  as 
for  the  preparation  of  serum-albumin  from  serum.  The  casein  and 
the  globulin  are  removed  by  MgSOi  in  substance  and  the  filtrate 
treated  as  previously  stated  (page  61). 

The  occurrence  of  other  albuminous  bodies,  such  as  albumoses  and  peptones, 
in  milk  has  not  been  positively  proved.  These  bodies  are  easily  produced  as 
laboration  products  from  the  other  albuminous  bodies  of  the  milk.  Such  a 
laboration  product  is  Millon's  and  CoMAiiiLE's  lactoprotein,  which  is  a  mix- 
ture of  a  little  casein  with  changed  albumin,  and  which  is  formed  by  the 
chemical  operations. 

Milk-sugar,  lactose,  CigHaaOu  +  HgO.  This  sugar  with  the 
absorption  of  water  can  be  split  into  two  glucoses,  dextrose  and 
galactose.  It  yields  by  the  action  of  dilute  nitric  acid,  besides 
carbon  dioxide,  oxalic  acid,  tartaric  acid,  saccharic  acid,  and  racemic 
acid,  a  crystallizable  mucic  acid,  which  is  nearly  insoluble  in  cold 
water  and  in  alcohol,  and  which  may  also  be  obtained  from  dulcite. 


MILK.  307 

gum,  and  vegetable  mucus.  By  the  action  of  sodium  amalgam  on 
milk-sugar  we  obtain  dulcite,  mannite,  lactic  acid,  and  other  pro- 
ducts. By  the  action  of  alkalies  we  obtain  lactic  acid  among  other 
products. 

Milk-sugar  occurs  in  all  milks.  It  has  also  been  found  in  the 
urine  of  pregnant  women.  According  to  Bouchardat,  it  also 
occurs  in  the  ripe  fruit  of  the  achras  sapota. 

Milk-sugar  occurs  ordinarily  as  colorless  rhombic  crystals  with 
1  mol.  of  water  of  crystallization,  which  is  driven  off  by  slowly  heat- 
ing to  100°  C,  but  more  easily  at  130°-140°  C.  At  170°  to  180°  C. 
it  is  converted  into  a  brown  amorphous  mass,  lactocaramel,  CsHioOs. 
Milk-sugar  dissolves  in  6  parts  cold  and  in  2.5  parts  boiling  water; 
it  has  a  faint  sweetish  taste.  It  does  not  dissolve  in  ether  or  abso- 
lute alcohol.  Its  solutions  are  dextro-gyrate.  The  rotary  power, 
which,  on  heating  the  solution  to  100°  C.  becomes  constant,  is  a  (B) 
=  +  52.5°.  Milk-sugar  combines  with  bases  ;  the  alkali  combina- 
tions are  insoluble  in  alcohol. 

Milk-sugar  is  not  fermentable  with  pure  yeast.  It  undergoes, 
on  the  contrary,  alcoholic  fermentation  by  the  action  of  certain 
schizomycetes,  and  lactic  acid  is  then  produced  thereby.  The  prep- 
aration of  milk-wine,  "  kumyss"  txom  mare's  milk  and  "JcepMr" 
from  cow's  milk  is  based  upon  this  fact.  Micro-organisms  pro- 
duce a  lactic  fermentation  in  lactose,  and  this  explains  the  ordinary 
souring  of  milk. 

Lactose  responds  to  the  reactions  of  grape-sugar,  such  as 
Moore's  or  Trommer's  and  the  bismuth  test,  which  will  all  be 
described  in  Chapter  XIV  on  the  urine.  It  also  reduces  mercuric 
oxide  in  alkaline  solutions.  After  warming  with  phenylhydrazin 
acetate  it  gives  on  cooling  a  yellow  crystalline  precipitate  of  phenyl- 
lactosazon,  C24H32N4O9  (see  Chap.  XIV  on  sugar  in  the  urine). 
It  differs  from  cane-sugar  by  giving  positive  reactions  with 
Moore's  and  the  bismuth  test,  and  also  that  it  does  not  darken 
when  heated  with  anhydrous  oxalic  acid  to  100°  C.  It  differs  from 
grape-sugar  and  maltose  by  its  solubility  and  crystalline  form  ;  but 
especially  by  its  not  fermenting  with  yeast  and  by  yielding  mucic 
acid  with  nitric  acid. 

For  the  preparation  of  milk-sugar  we  make  use  of  the  by-product 
in  the  preparation  of  cheese,  the  sweet  whey.     The  albumin  is  re- 


308  PHYSIOLOGICAL   CHEMISTRT. 

moved  by  coagulation  with  heat  and  the  filtrate  evaporated  to  a- 
syrup.  The  crystals  which  separate  after  a  certain  time  are  recrystal- 
lized  from  water  after  decolorizing  with  animal  charcoal.  A  pure 
preparation  maybe  obtained  from  the  commercial  milk-sugar  by 
repeated  recrystallization.  The  quantitative  estimation  of  milk- 
sugar  may  in  part  be  performed  by  the  polaristrobometer  and  partly 
by  means  of  titration  with  Feeling's  solution.  10  cc.  of  Feeling's 
solution  corresponds  to  0.067  grm.  milk-sugar  (in  regard  to  Fee- 
ling's solution  and  the  titration  of  sugar,  see  Chapter  XIV). 

RiTTHATiSEN  has  found  another  carbohydrate  in  milk  which  is  soluble 
in  water,  non-crystallizable,  which  has  a  faint  reducing  action,  and  which 
yields  on  boiling  with  an  acid  a  body  having  a  greater  reducing  power.  Land- 
WEMK  considers  this  as  an  animal  gum. 

The  mineral  bodies  of  milk  will  be  treated  in  connection  with 
its  quantitative  composition. 

The  methods  for  the  quantitative  analysis  of  milk  are  numerotis, 
and  as  they  all  cannot  be  treated  of  here,  we  will  give  the  chief 
points  of  a  few  of  the  most  trustworthy  and  most  frequently- 
employed  methods. 

In  determining  the  solids  a  carefully-weighed  quantity  of  milk 
is  mixed  with  an  equal  weight  of  heated  sand,  fine  glass  powder,  or 
asbestos.  The  evaporation  is  first  done  on  the  water-bath  and 
finished  in  a  current  of  carbon  dioxide  or  hydrogen  not  above 
100°  C. 

The  mineral  bodies  are  determined  by  ashing  the  milk,  using 
the  precautions  suggested  in  the  text-books.  The  results  obtained 
for  the  phosphoric  acid  are  incorrect  on  account  of  the  burning  of 
phosphorized  bodies,  such  as  casein  and  lecithin.  We  must  there- 
fore, according  to  Soldnbr,  subtract  25^  from  the  total  phosphoric 
acid  found  in  the  milk.  The  quantity  of  sulphate  in  the  ash  also 
depends  on  the  burning  of  the  albumins. 

In  the  determination  of  the  total  amoicnt  of  albuminous  bodies 
we  make  use  of  Eitthausen's  method,  namely,  precipitate  the 
milk  with  copper  sulphate.  This  method  gives  incorrect  results 
because  the  copper  hydroxide  does  not  give  up  all  its  water  of 
hydration  on  drying  the  precipitate,  but  only  after  ashing  the 
same.  The  results  for  the  proteids  are  therefore  somewliat  too 
high. 

The  method  of  Puls  and  Stenberg  consists  in  first  diluting 
the  neutralized  milk  with  some  water  and  then  treating  with  alco- 
hol until  the  mixture  contains  70-85  vols,  per  cent  alcohol.  The 
precipitate  is  collected  on  a  filter,  washed  with  warm  70^  alcohol, 
extracted  with  ether,  dried,  weighed,  burnt,  and  the  residue  re- 
weighed.     The  traces  of  albumin  which  remain  in  the  filtrate  and 


MILK.  309 

■wash-liquor  are  precipitated  by  tannic  acid  (see  page  21).  63^  of 
the  tannic  acid  precipitate  is  considered  as  albumin,  and  this  must 
be  added  to  the  albumin  iound  directly.  This  method  gives  exact 
and  good  results. 

According  to  the  method  of  Sebelien,  3-5  grms.  of  milk  are 
diluted  with  an  equal  volume  of  water,  a  little  common-salt  soUition 
added,  and  precipitated  with  an  excess  of  tannic  acid.  The  precipi- 
tate i^  washed  with  cold  water,  and  then  the  quantity  of  nitrogen 
determined  by  Kjeldahl's  method.  The  total  nitrogen  found 
when  multiplied  by  6.37  (casein  and  lactalbumin  contain  both 
15.7^  nitrogen)  gives  the  total  quantity  of  albuminous  bodies.  This 
easily- executed  method  gives  very  good  results,  but  until  the  quan- 
tity of  nitrogen  in  the  albuminous  bodies  of  other  varieties  of  milk 
has  been  exactly  determined  this  method  cannot  be  nsed  except 
for  the  analysis  of  cow's  milk. 

To  determine  the  casein  and  albumins  separately  we  may  make 
use  of  the  method  first  suggested  by  Hoppe-Seyler  and  Tolmat- 
SCHEFF,  in  which  the  casein  is  precipitated  by  magnesium  sulphate. 
According  to  Sebelien,  the  milk  is  diluted  with  its  own  volume 
of  a  saturated  magnesium-sulphate  solution,  then  saturated  with 
the  salt  in  substance,  the  precipitate  filtered  and  washed  with  a 
saturated  magnesium-sulphate  solution.  The  nitrogen  is  deter- 
mined in  the  precipitate  by  Kjeldahl's  method,  and  the  quantity 
of  casein  determined  by  multiplying  the  result  by  6.37.  The  quan- 
tity of  lactalbumin  may  be  calculated  as  the  difference  between  the 
casein  and  the  total  albumin  found.  The  lactalbumin  may  also  be 
precipitated  by  tannic  acid  from  the  filtrate  containing  MgSOi  from 
the  casein  precipitate,  diluted  with  water,  and  the  nitrogen  deter- 
mined by  Kjeldahl's  method  and  the  result  multiplied  by  6.37. 
Sebelien's  method  is  only  suited  for  cow's  milk. 

The  quantity  of  globidins  in  milk  cannot  be  exactly  determined. 
A  minimum  result  can  be  obtained  by  first  precipitating  the  casein 
completely  by  NaCl  in  substance,  and  then  precipitating  the  glob- 
ulins in  the  filtrate  by  magnesium  sulphate  (Sebelien).  The 
casein  may  also  be  precipitated  from  the  diluted  milk,  and  the 
globulin  precipitated  after  neutralization  by  means  of  MgSOi.  In 
these  cases  we  obtain  somewhat  high  results,  because  of  the  pres- 
ence of  traces  of  casein  which  remain  behind. 

The  fat  is  determined  directly  by  thoroughly  extracting  the 
dried  milk  with  ether,  evaporating  the  ether  from  the  extract,  and 
weighing  the  residue.  The  fat  may  be  determined  by  aerometric 
means  by  adding  alkali  to  the  milk,  shaking  with  ether,  and  deter- 
mining the  specific  gravity  of  the  fat  solution  by  means  of  Soxh- 
let's  apparatus.  In  determining  the  amount  of  fat  in  a  large 
number  of  samples  the  lactokrit  of  De  Laval  may  be  used  with 
success.     The  milk  is  first  mixed  with  an  equal  volume  of  a  mix- 


310  PHYSIOLOGICAL  CHEMISTRY. 

ture  of  acetic  acid  and  concentrated  sulphuric  acid,  warmed  7-8 
minutes  on  the  water-bath,  the  mixture  placed  in  graduated  tubes, 
and  these  in  the  centrifugal  machine  at  +  50°  C.  The  height  of 
the  layer  of  fat  gives  its  quantity. 

In  determining  the  milk-sugar  first  the  albumin  is  removed. 
For  this  purpose  we  precipitate  either  with  alcohol,  which  must  be 
evaporated  from  the  filtrate,  or  by  diluting  with  water,  and  re- 
moving the  casein  by  the  addition  of  little  acid,  and  the  lactalbumin 
by  coagulation  at  a  boiling  heat.  The  sugar  is  determined  by 
titration  with  Fehling's  or  Knapp's  solution  (see  Chap.  XIV). 
The  principle  of  titration  is  the  same  as  for  the  titration  of 
sugar  in  urine:  10  c.c.  of  Feeling's  solution  corresponds  to 
0.067  grm.  milk-sugar;  10  c.c.  of  Knapp's  solution  corresponds  to 
0.0311-0.0310  grm.  milk-sugar,  when  the  saccharine  liquid  con- 
tains about  i-lfo  sugar.  In  regard  to  the  modus  operandi  of  the 
titration  we  must  refer  the  reader  to  more  complete  works  and  to 
Chapter  XIV. 

Instead  of  the  volumetric  determinations  the  following  steps 
may  be  taken:  A  measured  quantity  of  the  milk-sugar  solution  is 
treated  with  an  excess  of  Feeling's  solution,  boiled,  the  copper 
suboxide  filtered  and  reduced  in  a  current  of  hydrogen,  and  the 
metallic  copper  weighed.  Soxhlet  has  given  a  table  (Journal  fiir 
praktische  Chemie,  1880)  which  simplifies  the  calculations  in  such 
cases. 

The  sugar  may  also  be  determined  by  the  polariscope,  and  with 
ease,  because  the  filtrates  containing  milk-sugar  are  generally  color- 
less. The  determination  is  quickly  performed  but  does  not  give 
exact  results. 

The  quantitative  com.jjosition  of  cow's  milk  is  variable.  The 
average  obtained  by  Konig  is  as  follows  in  1000  parts  : 

Water.        Solids.        Casein.        Albumin.        Fats.        Sugar.        Salt. 
874.2  135.8  28.8  5.3  36.5  48.1  7.1 


34.1 


The  quantity  of  mineral  bodies  in  1000  parts  of  cow's  milk  is, 
according  to  the  analyses  of  Soldner,  as  follows  :  KgO  1.72, 
NagO  0.51,  CaO  1.98,  MgO  0.20,  P2O5  1.82  (after  correction  for 
the  nucleins),  CI  0.98  grms.  Bunge  found  0.0035  grm.  FejOs.  Ac- 
cording to  Soldner,  the  K,  Na  and  CI  are  found  in  the  same  quan- 
tities in  whole  milk  as  in  milk-serum.  Of  the  total  phosphoric 
acid  36-56^  is  not  dissolved  and  also  53-72^  of  the  lime.  A  part  of 
this  lime    is  combined  with   the  casein;    the  remainder  is  found 


MILK.  311 

united  with  the  phosphoric  acid  as  a  mixture  of  di-and  tri-calcium 
phosphate,  which  is  kept  dissolved  or  suspended  by  the  casein. 
The  bases  are  in  excess  of  the  mineral  acids  in  tlie  milk-serum.  The 
excess  of  the  first  is  combined  with  organic  acids  which  correspond 
to  2.5  p.  m.  citric  acid  (Soldner). 

The  gases  of  the  milk  consist  chiefly  of  CO2, besides  a  little  N 
and  traces  of  0.  Pfluger  found  10  vols,  per  cent  CO2  and  0.6  vol. 
per  cent  N,  calculated  at  0°  C.  and  760  mm.  pressure. 

The  variation  in  the  composition  of  cow's  milk  depends  on 
several  circumstances. 

The  colostrum,  or  the  milk  which  is  secreted  before  calving  and 
in  the  first  few  days  after,  is  yellowish,  sometimes  alkaline,  but  often 
acid,  of  high  specific  gravity,  1.046-1.080,  and  richer  in  solids  than 
ordinary  milk.  The  colostrum  contains,  besides  fat-globules,  an 
abundance  of  colostrum-corpuscles — nucleated  granular  cells  0.005- 
0.025  mm.  in  diameter  with  abundant  fat-grains  and  fat-globules. 
The  fat  of  colostrum  has  a  somewhat  higher-melting  point  and  is 
poorer  in  volatile  fatty  acids  than  the  fat  from  ordinary  milk 
(Nilson).  The  quantity  of  cholesterin  and  lecithin  is  generally 
greater.  The  most  apparent  difference  between  it  and  ordinary 
milk  is  that  colostrum  coagulates  on  heating  to  boiling  be- 
cause of  the  absolute  and  relatively  greater  quantities  of  globulin 
and  albumin  it  contains.  The  quantity  of  the  first  of  these  two 
albuminous  bodies  may  indeed  amount  to  several  per  cent  (Sebe- 
lien).  The  composition  of  colostrum  is  very  variable.  Konig 
gives  as  average  the  following  figures  in  1000  parts: 

Water.     Solids.     Casein.     Albumin  and  Globulin.     Fat.     Sugar.     Salts. 
740.5        259.5        46.6  136.2  34.3      26.6        15.8 

The  properties  of  milk  are  changed  during  lactation  and  it 
becomes  richer  in  casein.  A  change  in  the  amount  of  fat  is  also 
sometimes  observed  (Emmerling).  Otherwise  we  often  say  that 
the  milk  becomes  poorer  in  fat  during  lactation  and  the  fat  defi- 
cient in  volatile  fatty  acids.  The  evening  milk  is  richer  in  fat  than 
the  morning  milk  (Alex.  Muller  and  Eisenstuck  ;  Nilson). 
The  race  of  the  animal  also  has  a  great  influence  on  the  milk. 

The  influence  food  exercises  upon  milk  will  be  discussed  in  con- 
nection with  the  chemistry  of  the  milk  secretion. 


Proteids. 

Fat. 

Sugar. 

Lactic  Acid. 

Salts. 

31.1 

7.4 

47.5 

.... 

7.4 

36.1 

367.5 

35.3 

.... 

6.1 

40.6 

9.3 

37.3 

3.4 

6.7 

8.5 

3.3 

47.0 

3.3 

6.5 

312  PHT8I0L0GIGAL   CHEMISTRT. 

In  the  following  we  give  the  average  composition  of  skimmed  milk  and 
certain  other  preparations  of  milk  (Konig). 

Water. 

Skimmed  milk 906.6 

Cream 655.1 

Butter  milk 903.7 

Whey 933.4 

KuMYSS  and  kephir  are  obtained  as  above  stated,  by  the  alcoholic  and 
lactic  acid  fermentation  of  the  milk-sugar,  the  first  from  mare's  milk  and  the 
last  from  cow's  milk.  Large  quantities  of  carbon  dioxide  are  formed  hereby, 
and  also  the  albuminous  bodies  of  the  milk  are  partly  converted  into  albumoses 
and  peptones,  which  increases  the  digestibility.  The  quantity  of  lactic  acid 
in  these  preparations  may  be  about  10-30  p.  m.  The  quantity  of  alcohol  varies 
from  10  to  35  p.  m. 

Milk  from  other  Animals.  Goat's  milk  has  a  more  yellowish  color  and 
another,  more  specific,  odor  than  cow's  milk.  The  coagulation  obtained  by 
acid  or  rennet  is  more  solid  and  is  harder  than  that  from  cow's  milk.  Sheep's 
milk  is  similar  to  goat's  milk,  but  has  a  higher  specific  gravity  and  contains 
&  greater  amount  of  solids. 

Mare's  milk  is  alkaliue  and  contains  a  casein  which  is  not  precipitated  by 
acids  in  lumps  or  solid  masses,  but,  like  the  casein  from  woman's  milk,  in  fine 
flakes.  This  casein  is  only  incompletely  precipitated  by  rennet,  and  it  is  very 
similar  also  in  other  respects  to  the  casein  of  human  milk.  According  to  Biel, 
the  casein  from  mare's  and  cow's  milk  is  the  same,  and  the  different  behavior 
of  the  two  varieties  of  milk  is  due  to  different  amounts  of  salts  and  to  a  dif- 
ferent relation  between  the  casein  and  the  albumin.  The  milk  of  the  ass  is 
similar  to  human  milk. 

The  milk  of  carnivora,  the  bitch  and  cat,  are  acid  in  reaction  and  very 
rich  in  solids.  The  composition  of  the  milk  of  these  animals  varies  very  much 
with  the  composition  of  the  food. 

To  illustrate  the  composition  of  the  milk  of  other  animals  the  following 
figures,  the  compilation  of  Konig,  will  be  given.  As  the  milk  of  each  variety 
of  animal  may  have  a  variable  composition,  these  figures  may  only  be  con- 
sidered as  examples  of  the  composition  of  milk  of  different  kinds. 


Milk  of  the 

Water. 

Solids. 

Proteids. 

Fat. 

Sugar. 

Salts. 

Dog. .  .  . 

754.4 

345.6 

99.1 

95.7 

31.9 

7.3 

Cat 

816.3 

183.7 

90.8 

33.3 

49.1 

5.8 

Goat .... 

869.1 

130.9 

36.9 

40.9 

44.5 

8.6 

Sheep... 

835.0 

165.0 

57.4 

61.4 

39.6 

6.6 

Cow 

874.3 

135.8 

34.1 

36.5 

48.1 

7.1 

Horse.... 

900.6 

99.4 

18.9 

10.9 

66.5 

3.1 

Ass 

900.0 

100.0 

31.0 

13.0 

63.0 

3.0 

Pig 

833.7 

167.3 

60.9 

64.4 

40.4 

ie.6 

Human  Milk. 


Woman's  milk  generally  differs  from  cow's  milk  in  having  an 
alkaline  reaction  and  larger  fat-globules.  Their  number,  according 
to  BoucHUT,  is  in  most  cases  1-2  millions  in  1  c.mm.     The  specific 


MILK.  313 

gravity  of  woman's  milk  is  between  1.036  and  1.035,  but  varies 
generally  between  1.038  and  1.034.  This  milk  in  general  lias  a  less 
inclination  to  turn  acid,  and  it  therefore  does  not  coagulate  dis- 
tinctly. 

The  fat  from  human  milk  has  not  been  thoroughly  investigated. 
According  to  Hoppe-Seyler,  it  is  richer  in  fluid  fats  than  the  fat 
from  cow's  milk. 

The  essential  qualitative  difference  between  woman's  and  cow's 
milk  seems  to  lie  in  the  proteids,  or  in  the  more  accurately  deter- 
mined casein.      A  number  of   investigators,  such  as  Berzelius, 
Simon,  Biedert,  Langgard,  Makris,  and  others,  claim  that  the 
casein  from  woman's  milk  has  other  properties  than  that  from 
cow's   milk.      The  essential  differences    are  the  following :    The 
casein  from  woman's  milk   is  precipitated  with  greater  difficulty 
with  acids  or  salts ;   it  does  not  coagulate  regularly  in  the  milk 
after  the  addition  of  rennet ;  it  may  be  precipitated  by  gastric 
juice,  but  dissolves  completely  and  easily  in  an  excess  of  the  same; 
the  casein  precipitate  produced  by  an  acid  is  more  easily  soluble  in 
an  excess  of  the  acid  ;  and  lastly,. the  clot  formed  from  the  casein 
does  not  appear  in  such  large  and  coarse  masses  as  the  casein  from 
cow's  milk,  but  is  more  loose  and  flocculent.     This  last-mentioned 
fact  is  of  great  importance,  since  it  explains  the  generally-admitted 
easy  digestibility  of  the  casein  from  woman's  milk.     The  question 
as  to  whether  the  above-mentioned  differences  depend  on  a  decided 
difference  in  the  two  caseins  or  only  on  an  unequal  relationship  be- 
tween the  casein  and  the  salts  in  the  two  varieties  of   milk,   or 
upon  other  circumstances,  has  not  been  sufficiently  investigated, 
and  doubtless  further  experiments   will    be  of  gi-eat  value.     We 
have  not,  up  to  the  present  time,  any  quite  trustworthy  analyses  of 
the   casein    from   woman's   milk,  but  it  seems  probable  that  the 
caseins  from  woman's  and  cow's  milk  are  not  identical  albuminous 
bodies.     Besides  casein,  woman's   milk  contains  lactalbumin,  and 
certain  investigators  maintain  that  they  have  found  relatively  lai-ge 
amounts  of  albumoses  and  peptones.      According  to  other  state- 
ments (DoGiEL  and  Hofmeister),  no  peptones  occur  in  woman's 
milk,  and   the  methods  employed  for  detecting  albumoses  seem  to 
have  given  no  positive  results.     The  albuminous  bodies  of  woman's 
milk  require  more  thorough  investigation.     The  total  quantity  of 


314 


PHT8I0L0QICAL   CHEMISTRY. 


milk  secreted  by  both  mammary  glands  amounts  to  500-1500  grms. 
in  two  hours. 

The  quantitative  composition  of  looman's  milk  is,  even  after 
those  differences  are  eliminated  which  depend  on  the  imperfect 
analytical  methods  employed,  variable  to  such  an  extent  that  it  is 
impossible  to  give  any  average  results.  Eliminating  certain  of  the 
older,  incorrect  analyses,  we  here  give  only  examples  from  the  aver- 
age results  of  a  few  modern  investigators,  taken  from  a  very  large 
number  of  analyses  (Pfeiffer,  Leeds).  The  following  figures  are 
parts  per  1000. 


Water. 


876.0 


891.0 

872.4 

892.0 

890.6 

877.90 

867.32 


Solids. 


124.0 


109.0 
127.6 
108.0 
109.4 


132.68 


Proteids. 


22.10 
23.60 
17  90 
19.00 
16  13 
17.24 
25.30 
19.95 


Fat. 


38.10 
25.60 
33.00 
43.20 
33.28 
29  15 
38.90 
41.31 


Choles- 
terin. 


0.32 


60.90 
55.60 
53.90 
59.80 
57.94 
59.92 
55.40 
69.36 


Salts. 


2.90 


4.20 
2.60 
1.65 
2.09 
2.50 
2.00 


BlEIi 

tolmatschefp 

Gkrber 

Christenn 

20-30yearsold|p^^^^^^^ 

Mendes  de  Leon 
Leeds 


Although  the  composition  of  woman's  milk  is  very  variable, 
and  notwithstanding  that  in  a  few  cases  higher  results  (about  40 
p.  m.)  have  been  obtained,  by  later  analyses,  for  albuminous  bodies, 
still  it  seems  that  woman's  milk  in  general  contains  less  proteids 
and  more  sugar  than  cow's  milk.  The  quantity  of  casein  is  not 
only  absolutely  but  also  relatively  smaller  in  proportion  to  the 
quantity  of  albumin  in  woman's  than  in  cow's  milk. 

A  further  difference  between  woman's  and  cow's  milk  is  that 
the  first  is  richer  in  lecithin  but  poorer  in  mineral  bodies,  especially 
CaO  and  P2O5  (it  contains  only  \  and  \,  respectively,  of  the  corre- 
sponding quantity  of  these  mineral  bodies  in  cow's  milk). 

In  regard  to  the  quantity  of  mineral  bodies  in  woman's  milk  the 
analyses  of  Bunge  are  most  reliable.  He  analyzed  the  milk  of  a 
woman,  fourteen  days  after  delivery,  whose  diet  contained  very  little 
common  salt  for  four  days  previous  to  the  analysis  {A),  and  again 
three  days  later  after  a  daily  addition  of   30  grms.  NaCl  to  the 


MILK. 


315 


food  {B).    BuNGE  found  the  following  figures  in  1000  parts  of  the 

milk  : 

A  B 

KaO 0.780  0.703 

NaaO 0.232  0.257 

CaO 0.328  0.343 

MgO 0.064  0.065 

Fe^Oa 0.004  0.006 

PaOs 0.473  0.469 

CI 0.438  0.445 

The  relatiouship  of  the  two  bodies,  potassium  and  sodium,  to 
each  other  may,  according  to  Bunge,  vary  considerably  (1.3-4.4 
equivalents  potash  to  1  of  soda).  By  the  addition  of  salt  to  the 
food  the  quantity  of  sodium  and  chlorine  in  the  milk  increases, 
while  the  quantity  of  potassium  decreases.  The  gases  of  woman's 
milk  have  not  been  investigated. 

The  proper  treatment  of  cow's  milk  by  diluting  with  water  and 
by  certain  additions  in  order  to  render  it  a  proper  substitute  for 
woman's  milk  in  the  nourishment  of  babes  cannot  be  determined 
before  the  difference  in  the  albuminous  bodies  of  these  two  kinds 
of  milk  has  been  completely  studied. 

The  period  of  lactation  acts  essentially  the  same  on  woman's  as 
on  cow's  milk. 

The  colustrum  has  a  higher  specific  gravity,  1.040-1.060,  a 
greater  quantity  of  coagulable  proteids,  and  a  deeper  yellow  color 
than  ordinary  woman's  milk.  Even  a  few  days  after  delivery  the 
color  becomes  less  yellow,  the  quantity  of  albumin  less,  and  the 
number  of  colostrum-corpuscles  diminishes.  Clemm  has  analyzed 
the  colostrum  at  different  periods  before  and  after  delivery,  and 
the  following  are  his  results  in  parts  per  1000 : 


Water 

Solids 

Casein 

Albumin . . . 
Fat. ....... 

Milk-sugar, 
Salts 


Four  Weeks  before 
Delivery. 


945.2 

54.8 


28.8 
7.3 

17.3 
4.4 


852.0 
148.0 

"69.6' 

41.3 

39.5 

4.4 


Seventeen 

Days 

before 

Delivery. 


851.7 
148.3 


74.8 

30.2 

43.7 

4.5 


Nine  Days 
before 
Delivery. 


858.8 
141.2 


80.7 

23.5 

36.4 

5.4 


Twenty- 
four  Hours 
after 
Delivery. 


843.0 
157.0 


5  1 


Two  Days 

after 
Delivery. 


867.9 
132.1 

21.8 

'  48.6" 
61.0 


316  PHYSIOLOGICAL   CHEMISTRY. 

The  total  quantity  of  albumins  seems  to  decrease  with  the  dura- 
tion of  lactation.  Pfeiffer  found  the  average  figures  for  the 
total  proteids  for  the  two  first  days,  the  fii-st  week,  the  second 
week,  the  second  month,  and  the  seventh  month  to  be  86.04, 
34.42,  22.88,  18.43,  and  15.21  p.  m.,  respectively.  Simon  claims 
that  the  amount  of  casein  is  smaller  in  the  first  stages  of  lactation 
and  then  increases  considerably;  but  according  to  Pfeiffer,  just 
the  reverse  takes  place.  The  amount  of  fat  shows  no  regular  and 
constant  variation  during  lactation.  According  to  Vernois  and 
Becquerel,  the  quantity  of  milk-sugar  decreases  in  the  first 
months,  but  increases  in  the  eighth  to  the  tenth  month.  According 
to  Pfeiffer,  the  quantity  of  sugar  increases  from  the  delivery  to 
the  third  to  fourth  month,  and  then  it  is  somewhat  variable. 

The  two  mammary  glands  of  the  same  woman  may  yield  somewhat 
different  milk,  as  shown  by  Sourdat  and  later  by  Brunner.  Also  the 
different  portions  of  milk  from  the  same  milking  may  have  different  composi- 
tions. The  first  portions  are  always  poorer  in  fat  (Parmentier,  Peligot, 
and  others). 

According  to  l'Heritier,  Vernois,  and  Becquerel,  the  milk  of  blonds 
contains  less  casein  than  that  of  brunettes,  a  difference  which  Tolmatbcheff 
could  not  substantiate.  Women  of  weak  constitutions  yield  a  milk  richer  in 
solids,  especially  in  casein,  than  women  with  strong  constitutions  (V.  and  B.). 

According  to  Veristois  and  Becquerel,  the  age  of  the  woman  has  an  effect 
on  the  composition  of  the  milk,  so  that  we  find  a  greater  quantity  of  proteids 
and  fat  in  women  15-20  years  old  and  a  smaller  quantity  of  sugar.  The 
smallest  quantity  of  proteids  and  the  greatest  quantity  of  sugar  are  found  at 
20  or  from  25-30  years  of  age.  According  to  V.  and  B.,  the  milk  with  the 
first-born  is  richer  in  water— with  a  proportionate  diminution  of  the  quantity 
of  casein,  sugar,  and  fat— than  after  several  deliveries. 

The  influence  of  menstruation  seems  to  slightly  diminish  the  milk-sugar 
and  to  considerably  increase  the  fat  and  casein  (V.  and  B.). 

Witch's  Milk  is  the  secretion  of  the  mammary  glands  of  new-born  children 
of  both  sexes  immediately  after  birth.  This  secretion  has  from  a  qualitative 
standpoint  the  same  constitution  as  milk,  but  may  show  important  differences 
and  variations  from  a  quantitative  point  of  view.  Schlossberger  and  Haupf, 
Gubler  and  Quevenne,  and  v.  Gesner  have  made  analyses  of  this  milk  and 
give  the  following  results  :  10.5-28  p.  m.  proteids,  8.2-14.6  p.  m.  fat,  and  9-60 
p.  m.  sugar. 

As  milk  is  the  only  form  of  nourishment  during  a  certain  period 
of  the  life  of  man  and  mammalia,  it  must  contain  all  the  nutritious 
bodies  necessary  for  life.  This  fact  is  shown  by  the  milk-contain- 
ing  representives  of  the  three  chief  groups  of  organic-nutritive 
substances,  proteids,  carbohydrates,  and  fat;  and  all  milk  seems 
to  contain  also  some  lecithin.     The  mineral  bodies  in  milk  must 


MILK.  317 

also  occur  in  proper  proportion,  and  on  this  point  the  observations 
of  BuNGE  on  dogs  are  of  special  interest.  He  found  that  the 
mineral  bodies  of  the  milk  occur  in  about  the  same  relative  propor- 
tion as  they  do  in  the  body  of  the  sucking  animal.  Bunge  found 
in  1000  parts  of  the  ash  the  following  results  {A  represents  results 
from  the  new-born  dog  and  B  the  milk  from  the  bitch) : 

A  B 

K,0 114.2  149.8 

Na^O 106.4  88.0 

CaO 295.2  272.4 

MgO 18.2  15.4 

FesOa 7.2  1.2 

P2O5 394.2  342.2 

CI 83.5  169.0 

BuxGE  explains  the  fact  that  the  milk-ash  is  richer  in  potash 
and  poorer  in  soda  than  the  new-born  animal  by  saying  that  in  the 
growing  animal  the  growing  muscles  rich  in  potash  relatively 
increase  and  the  cartilage  rich  in  soda  relatively  decreases.  Bunge 
seeks  to  explain  the  high  amount  of  chlorine  in  the  milk-ash  also 
teleologically  by  the  statement  that  the  chlorides  not  only  serve  to 
build  up  the  tissues,  but  are  indispensable  in  the  secretions  of  the 
kidneys.  In  regard  to  the  amount  of  iron  we  fiud  an  unexpected 
condition,  the  ash  of  the  new-born  animal  containing  six  times  as 
much  as  the  milk-ash.  This  condition  Bukge  explains  by  the  fact 
founded  on  his  and  Zalesky's  experiments,  that  the  quantitv  of 
iron  in  the  total  organism  is  highest  at  birth.  The  new-born 
animal  has  therefore  a  storage  of  iron  for  the  growth  of  its  organs 
even  at  its  birth. 

The  influence  of  the  food  on  the  composition  of  the  milk  is  of 
interest  from  many  points  of  view  and  has  been  the  subject  of 
many  investigations.  From  these  investigations  we  learn  that  in 
human  beings  as  well  as  in  animals  an  insufficient  diet  decreases 
the  quantity  of  milk,  and  the  quantity  of  solids  in  the  same,  while 
abundant  food  increases  both.  From  the  observations  of  Decaisxe 
on  nursing  women  during  the  siege  of  Paris  in  1871,  the  quantity 
of  casein,  fat,  sugar,  and  salts,  but  especially  the  fat,  was  found  to 
decrease  with  insufficient  food,  while  the  quantity  of  lactalbumin 
was  found  to  be  somewhat  increased.  Food  rich  in  proteids  in- 
creases the  quantity  of  milk,  and  also  the  solids  contained,  especially 


318  PHT8I0L00ICAL  CHEMISTRY. 

the  fat  (as  shown  in  women  by  Zalesky,  in  sheep  by  Stolzmann, 
Weiske,  Schrodt  and  Dehmel  and  Munk,  in  dogs  by  Poggiale 
and  SsuBBOTiN,  in  cows — at  least  in  most  cases — by  KiJHN  and  his 
pupils).  An  increase  in  the  quantity  of  casein,  and  a  decrease  in  the 
albumin  and  the  sugar  in  cow's  milk  after  food  containing  an  excess 
of  proteids  has  been  observed  by  KuHisr  and  his  pupils.  The  quan- 
tity of  sugar  in  woman's  milk  is  found  by  certain  investigators  to  be 
increased  after  food  rich  in  proteids,  while  others  claim  it  is  dimin- 
ished. Food  rich  in  fat  may  in  sheep,  as  observed  by  Stolzmann" 
Weiske,  Schrodt  and  Dehmel,  cause  an  increase  in  the  quantity  of 
fat  in  the  milk.  An  increase  in  the  quantity  of  fat  in  cow's  milk  be- 
cause of  an  addition  of  fat  to  the  fodder  has  only  been  observed  after 
a  previous  insufficient  diet,  but  not  after  a  sufficient  and  rich  diet 
(KiJHif  and  FLEiscHMAiirN).  After  feeding  with  palm-oil  cake  a 
one-sided  increase  in  the  fat  of  cow's  milk  was  observed  by  KiJHiS". 
The  presence  of  large  quantities  of  carbohydrates  in  the  food  seems 
to  cause  no  constant,  direct  action  on  the  quantity  of  the  milk-con- 
stituents. In  carnivora  the  secretion  of  milk-sugar  proceeds  unin- 
terrupted on  a  diet  consisting  exclusively  of  lean  meat.  Watery 
food  gives  a  milk  containing  an  excess  of  water  of  little  value.  In 
the  milk  from  cows  which  were  fed  on  distillers'  grains  Commaille 
found  906.5  p.m.  water,  26.4  p.m.  casein,  4.3  p.m.  albumin,  18.2 
p.  m.  fat,  and  33.8  p.m.  sugar.  Such  milk  has  a  peculiar  sour, 
sharp  after-taste. 

'Chemistry  of  the  Milk- Secretion.  That  the  actually-dissolved 
constituents  occurring  in  milk  pass  into  the  secretion,  not  alone  by 
filtration  or  diffusion,  but  more  likely  are  secreted  by  a  specific 
secretory  activity  of  the  glandular  elements,  is  shown  by  the  fact 
that  milk  sugar,  which  is  not  found  in  the  blood,  is  to  all  appear- 
ances formed  in  the  glands  themselves.  A  further  proof  lies  in 
the  fact  that  the  lactalbumin  is  not  identical  with  serum-albumin 
(Sebelien)  ;  and  lastly,  as  Bunge  has  shown,  the  mineral  bodies 
secreted  by  the  milk  are  in  quite  different  proportions  than  to  those 
in  the  blood-serum. 

Little  is  known  in  regard  to  the  formation  and  secretion  of  the 
specific  constituents  of  milk.  The  older  theory,  that  the  casein  was 
produced  from  the  lactalbumin  by  the  action  of  an  enzyme,  is  incor- 
rect and  originated  probably  from  mistaking  an  alkali-albuminate 


MILK.  319 

for  casein.  Bettei*  founded  is  the  statement  that  the  casein  origi- 
nates from  the  protoplasm  of  the  gland  cells,  which  seem  to  consist 
of  casein  or  a  substance  related  to  it.  The  previously  (page  300) 
mentioned  nucleoalbumin  of  the  gland-cells  appears  to  be  related 
to  casein,  and  it  may  possibly  form  its  mother  substance.  There 
does  not  seem  to  be  any  doubt  that  the  protoplasm  of  the  cells 
takes  part  in  the  secretion  in  such  a  manner  that  it  becomes  itself 
a  constituent  of  the  secretion.  According  to  Heidenhain,  the 
alveoles  contain  a  simple  layer  of  cells,  which,  in  the  inactive  gland, 
are  flat,  polyhedrous,  and  with  single  nucleus,  while  in  the  active 
gland  they  often  have  several  neuclei,  are  rich  in  albumin,  and  are 
high  and  cylindrical  in  form.  In  the  inner  part  of  the  cell  turned 
towards  the  cavity  of  the  acinus,  single  fat-granules  are  formed 
during  the  secretion  which  are  broken  off  with  the  edge  of  the  cells. 
The  broken-off  or  destroyed  cell-substance  in  the  secretion  dissolves 
in  the  milk,  filling  the  lumen  of  the  acinus,  while  the  cells  take  up 
nutrition  by  their  outer  parts,  and  grow,  and  replace  the  inner  parts 
used  in  the  secretion.  This  reminds  us  of  the  action  of  the  pan- 
creas-cells in  the  secretion  of  the  pancreatic  juice.  The  colostrum- 
corpuscles  are  not,  according  to  Heidenhain",  degenerated  fat- 
cells,  but  are  contractile  elements  originating  from  the  epithelium, 
which  take  up  finely-divided  fat  and  thereby  obtain  their  quantity 
of  fat-globules. 

That  the  milk-fat  is  produced  by  a  formation  of  fat  in  the  proto- 
plasm, and  that  the  fat-globules  are  set  free  by  their  destruction,  is 
a  generally-admitted  opinion  which,  however,  does  not  exclude  the 
possibility  that  the  fat  is  in  part  taken  up  by  the  glands  from  the 
blood  and  eliminated  with  its  secretion.  A  formation  of  fat  from 
carbohydrates  in  the  animal  organism  is  at  the  present  day  consid- 
ered as  positively  proved,  and  it  is  also  possible  that  the  milk-glands 
also  produce  fats  from  the  carbohydrates  brought  to  them  by  the 
blood.  It  is  a  well-known  fact  that  an  animal  gives  off  for  a  long 
time,  daily,  considerably  more  fat  in  the  milk  than  it  receives  as 
food,  and  tins  proves  that  at  least  a  part  of  the  fat  secreted  by  the 
milk  is  produced  from  proteids  or  carbohydrates,  or  perhaps  from 
both.  The  question  as  to  how  far  this  fat  is  produced  directly  in 
the  milk-glands,  or  from  other  organs  and  tissues,  and  brought  to 
the  gland  by  means  of  the  blood,  cannot  be  decided. 


320  PHYSIOLOGICAL   CHEMISTRY. 

The  origin  of  the  milk-sugar  is  not  known.  Muntz  calls  atten- 
tion to  the  fact  that  a  quantity  of  very  widely-diffused  bodies  in 
the  vegetable  kingdom — vegetable  mucus,  gums,  pectin  bodies — 
yield  galactose  as  products  of  decomposition,  and  he  believes,  there- 
fore, that  the  milk-sugar  may  be  formed  in  herbivora  by  a  synthesis 
from  dextrose  and  galactose.  Tliis  origin  of  milk-sugar  does  not 
answer  for  carnivora,  as  they  produce  milk-sugar  when  fed  on  food 
consisting  entirely  of  lean  meat.  The  observations  of  Bert  and 
Thierfelder  that  a  mother-substance  of  the  milk-sugar,  a  saccha- 
rogen,  occurs  in  the  glands  cannot,  as  the  nature  of  this  mother-sub- 
stance is  still  unknown,  give  further  explanation  as  to  the  formation 
of  milk-sugar.  The  question  whether  the  above  (page  300)  mentioned 
proteid,  which  yields  a  reducible  substance  when  boiled  with  dilute 
acids,  has  anything  to  do  with  the  formation  of  milk-sugar  cannot 
be  answered  until  further  thorough  investigations  have  been  made 
on  this  subject. 

The  passage  of  foreign  substances  into  the  milk  stands  in  close 
connection  with  the  chemical  processes  of  the  milk-secretion. 

It  is  a  well-known  fact  that  milk  acquires  a  foreign  taste  from 
the  food  of  the  animal,  which  is  in  itself  a  proof  that  foreign  bodies 
pass  into  the  milk.  This  fact  becomes  of  special  importance  in 
reference  to  such  injurious  substances  as  may  be  introduced  into 
the  organism  of  the  nursing  child  by  means  of  the  milk. 

Among  these  substances  may  be  mentioned  opium  and  mor- 
phine, which  after  large  doses  pass  into  the  milk  and  act  on  the 
child.  Alcohol  may  pass  into  the  milk  in  such  large  quantities 
that  it  produces  a  stupefying  effect  on  the  child.  Milkirom  cattle 
fed  on  distiller's  grains  may  also  contain  alcohol. 

Among  the  inorganic  bodies  we  find  iodine,  arsenic,  bismuth, 
antimony,  zinc,  lead,  mercury,  and  iron  in  the  milk.  After  inunc- 
tion-cures Paschkis  and  Vajda  detected  mercury  in  the  milk.  In 
icterus  neither  the  bile-acids  nor  bile-pigments  pass  into  the  milk. 

Under  diseased  conditions  no  constant  change  has  been  found  in  woman's 
milk.  In  isolated  cases  ScklossbekgeR:  Jolt  and  Filhol  have  observed 
indeed  an  essential  declining  composition,  but  no  positive  conclusion  can  be 
derived  therefrom. 

The  changes  in  cow's  milk  have  also  been  little  studied.  In  tuberculosis  of 
the  udder  Storch  found  tubercule  bacilli  in  the  milk,  and  he  also  found  that 
the  milk  became  more  and  more  diluted  during  the  disease  with  a  serous  liquid 


MILK.  321 

similar  to  blood-serum,  so  that  the  glands,  instead  of  yielding  milk,  only  gave 
b  ood-serum  or  a  serous  fluid.  Husson  found  the  milk  from  cows  sick  with 
murrain  contained  more  proteids  but  considerably  less  fat  and  (in  difficult 
cases)  less  sugar  than  normal  milk. 

The  milk  may  be  blue  or  red  in  color,  due  to  the  development  of  micro- 
organisms. 

The  formation  of  concrements  in  the  exit-passages  of  the  cow's  udder  are 
often  observed.  They  consist  chiefly  of  calcium  carbonate,  or  of  carbonate 
and  phosphate  with  only  a  small  amount  of  organic  substances. 


OHAPTEE  XIII. 
THE  SKIN  AND  ITS   SECRETIONS. 

If  the  structure  of  the  skin  of  man  and  vertebrates  many- 
different  kinds  of  substances  occur  which  have  already  been 
treated  of,  such  as  the  constituents  of  the  epidermis  formation,  the 
connective  and  fatty  tissues,  the  nerves,  muscles,  etc.  Among 
these  the  different  horn-formations,  the  hair,  nails,  etc.,  whose 
chief  constituent,  keratin,  has  been  spoken  of  in  another  chapter 
(Chap.  II),  are  of  special  interest. 

The  cells  of  the  horny  formation  show,  in  proportion  to  their 
age,  a  different  resistance  to  chemical  reagents,  especially  fixed 
alkalies.  The  younger  the  horn-cell  the  less  resistance  it  has  to 
the  action  of  alkalies;  with  advancing  age  the  resistance  becomes 
greater,  and  the  cell-membranes  of  many  horn-formations  are  nearly 
insoluble  in  caustic  alkalies.  Keratin  occurs  in  the  horn  formation 
mixed  with  other  bodies,  from  which  it  is  isolated  with  difficulty. 
Among  these  bodies  the  mineral  constituents  in  many  cases  occupy 
a  prominent  place  because  of  their  quantity.  Hair  leaves  on 
burning  5-70  p.  m.  ash  which  contains  in  1000  parts  230  parts 
alkali  sulphates,  140  parts  calcium  sulphate,  100  parts  iron  oxide, 
and  400  parts  silicic  acid.  Dark  hair  seems  generally,  but  not 
always,  to  yield  more  iron  oxide  on  burning  than  blond.  The 
nails  are  rich  in  calcium  phosphate,  and  the  feathers  rich  in  silicic 
acid. 

The  skin  of  invertebrates  has  been  the  subject,  in  a  few  cases, 
of  chemical  investigation,  and  in  these  animals  several  substances 
have  been  found,  of  which  a  couple,  though  little  studied,  are 
worth  discussing.  Among  these  bodies  tunicui,  which  is  found 
especially  in  the  tunic  of  the  tunicata,  and  the  widely-diffused 

•  323 


THE  SKIN  AND  ITS  SECRETIONS.  323 

chitin,  found  in   the  cuticle-formation  of  invertebrates,  are  of 
interest. 

Tanicin,  or  animal  cellulose,  occurs,  as  above  mentioned,  in  the  tunicata. 
According  to  Berthelot,  tunicin  differs  from  ordinary  cellulose,  being 
colored  yellow  by  iodine,  and  by  its  slower  conversion  into  sugar  on  boiling 
with  acids.  Otherwise  it  is  similar  to  ordinary  cellulose.  The  sugar 
obtained  by  boiling  tunicin  with  acids  is  grape  sugar,  according  to  Franchi- 

MONT. 

Chitin  is  not  found  in  vertebrates.  The  horny  layer  which  covers  the  inner 
side  of  the  gizzard  of  birds,  may  perhaps  consist  of  a  substance  related  to  chitin. 
In  invertebrates  the  chitin  occurs  in  many  classes  of  animals ;  it  cannot  be 
positively  asserted  that  true,  typical  chitin  is  found  elsewhere  than  in  articu- 
lated animals  ;  in  these  it  forms  the  chief  organic  constituent  of  the  shell,  etc. 

According  to  Sundwik,  the  composition  of  chitin  is  probably  CsoHiooNeOss 
+  ^(HjO),  where  n  may  vary  from  1  to  4.  On  boiling  with  mineral  acids  it 
decomposes  and  yields,  as  Ledderhose  has  shown,  glucosamine.  According 
to  Sundwik,  a  glucose  is  also  probably  hereby  produced.  He  also  claims  that 
chitin  is  an  amido  derivative  of  a  carbohydrate  of  the  formula  CeoHiooOeo. 

In  the  dry  state  chitin  forms  a  white,  brittle  mass  retaining  the  form  of 
the  original  tissue.  It  is  insoluble  in  boiling  water,  alcohol,  ether,  acetic  acid, 
dilute  mineral  acids,  and  dilute  alkalies.  It  is  soluble  in  concentrated  acids. 
It  is  dissolved  without  decomposing  in  cold  concentrated  hydrochloric  acid, 
but  is  decomposed  by  boiling  hydrochloric  acid.  When  chitin  is  dissolved  in 
concentrated  sulphuric  acid  and  the  solution  dropped  into  boiling  water  and 
then  boiled,  we  obtain  a  substance  (glucosamine  or  glucose)  which  reduces 
copper  suboxide  in  alkaline  solutions. 

Chitin  may  be  easily  prepared  from  the  wings  of  insects  or  from  the  shells 
of  the  lobster  or  the  crab,  the  last  mentioned  having  first  been  extracted  by  an 
acid  so  as  to  remove  the  lime-salts.  The  wings  or  shells  are  boiled  with 
caustic  alkali  until  they  are  white,  afterward  washed  with  water,  then  with 
dilute  acid  and  water,  and  lastly  extracted  with  alcohol  and  ether. 

Hyalin  is  the  chief  organic  constituent  of  the  walls  of  hydatid  cysts. 
Prom  a  chemical  point  of  view  it  stands  close  to  chitin,  or  between  it  and  the 
albumins.  In  old  and  more  transparent  sacks  it  is  tolerably  free  from  mineral 
bodies,  but  in  younger  sacks  it  contains  a  great  quantity  (16^)  of  lime-salts 
(carbonate,  phosphate,  and  sulphate). 

According  to  LtJCKE,  its  composition  is  : 

C 

From  old  cysts 45.3 

From  young  cysts 44.1 

It  differs  from  keratin  on  the  one  hand  and  from  albumin  on  the  other  by  the 
absence  of  sulphur,  also  by  its  yielding  a  variety  of  sugar  in  large  quantities 
(50^),  which  is  reducible,  fermentable,  and  dextro-gyrate  when  boiled  with 
dilute  sulphuric  acid.  It  dift'ers  from  chitin  by  the  property  of  being 
gradually  dissolved  by  caustic  potash  or  soda,  or  by  dilute  acids  ;  also  by 
its  solubility  on  heating  with  water  to  150°  C. 

The  coloring  matters  of  the  shin  and  hoi'n-formations  are  of 
different  kinds,  but  have  been  but  little  studied.  Those  occurring 
in  the  Malpighian  layer  of  the  skin,  especially  of  the  negro,  and 


H 

N 

0 

6.5 

5.2 

43.0 

6.7 

4.5 

44.7 

324  PHTSIOLOOICAL  CHEMISTRT. 

the  black  or  brown  pigment  occurring  in  the  liair  oelong  to  the 
group  of  coloring  matters  which  have  received  the  name  melanin. 

Melanins.  This  group  includes  several  different  varieties  of 
amorphous  black  or  brown  pigments  which  are  insoluble  in  water, 
alcohol,  ether,  chloroform,  and  dilute  acids,  and  which  occur  in 
the  skin,  hair,  epithelium-cells  of  the  retina,  in  sepia,  in  certain 
pathological  formations,  and  in  the  blood  and  urine  in  disease.  Of 
these  pigments  there  are  a  few,  such  as  the  melanin  of  the  eye 
and  that  from  the  melanotic  tumor  of  horses,  the  Mppomelaniii 
(Nencki  and  Berdez),  which  are  soluble  with  difficulty  in  alkalies, 
while  others,  such  as  the  pigment  of  the  hair  and  the  coloring 
matter  of  certain  pathological  swellings  in  man,  the  phymatorusin 
(Nencki  and  Berdez),  are  easily  soluble  in  alkalies. 

Among  the  melanins  there  are  a  few,  for  example  the  choroid 
pigment,  which  are  free  from  sulphur;  others,  on  the  contrary,  as 
the  pigment  of  the  hair  and  of  horse-hair,  are  rather  rich  in  sul- 
phur (2-4^),  while  the  phymatorusin  found  in  certain  swellings 
and  in  the  hair  (Nencki  and  Berdez,  K.  Morner)  is  very  rich  in 
sulphur  (8-10^).  If  any  of  these  pigments,  especially  the  phyma- 
torusin, contains  any  iron  or  not  is  an  important  though  disputed 
point,  for  it  leads  to  the  question  whether  these  pigments  are  formed 
from  the  blood-coloring  matters  (JSTencki  and  Sieber,  K.  Mor- 
ner). The  difficulties  which  attend  the  isolation  and  purification 
of  the  melanins  have  not  been  overcome  in  certain  cases,  while  in 
others  it  is  questionable  whether  the  final  product  obtained  has  not 
another  composition  than  the  original  coloring  matter,  owing  to 
the  energetic  chemical  processes  resorted  to  in  its  purification. 
Under  such  circumstances  it  seems  that  a  tabulation  of  the  analy- 
ses of  different  melanin  preparations  made  up  to  the  present  time 
are  of  secondary  importance. 

Among  the  above-mentioned  bodies  belonging  to  the  melanin 
group,  phymatorosin  prepared  by  Nencki  and  Sieber  from  mel- 
anotic tumors,  and  by  K.  Morner  from  the  tumors  and  the  urine 
of  a  patient,  seems  to  be  of  special  interest.  Phymatorusin  is  an 
amorphous  dark-bi'own  coloring  matter  soluble  in  alkalies  or  alkali 
carbonates,  but  insoluble  in  warm  50-75^  acetic  acid.  In  alkaline 
solution  it  shows  no  absorption-bands.  According  to  Nencki  and 
Sieber,  it  is  free  from  iron,  but  Morner,  on  the  contrary,  claims 


THE  SKIN  AND  ITS  SECRETIONS.  325 

that  it  does  contain  iron.  Mornek  found  for  this  coloring  mat- 
ter from  tumors  (A)  and  from  urine  (B)  the  following  composition 
calculated  on  the  substance  considered  as  ash-free  : 


A 

B 

c 

55.32—56.13 

55.76 

H 

5.65—  6.33 

5.95 

N 

13.30 

12.27 

S 

7.97 

9.01 

Fe 

0.063-0.081 

0.20 

Nencki  and  Sieber  have  also  shown  that  other  melanins,  not 
identical  with  phymatorusin,  occur  in  melanotic  sarcoma  of  man. 

The  coloring  matter  or  matters  of  human  hair  contain  a  low 
amount  of  nitrogen,  S.o^  (Sieber),  and  a  variable  but  high  amount 
of  sulphur,  2.71— i.  10^.  The  considerable  quantity  of  iron  oxide 
found  in  the  ash  does  not  seem  to  belong  to  the  coloring  matters. 

In  addition  to  the  coloring  matters  of  the  human  skin  we  may  also  here 
treat  of  the  pigments  found  in  the  skin  or  epidermis-formation  of  animals. 

The  beautiful  color  of  the  feathers  of  many  birds  depends  in  certain  cases 
on  purely  physical  causes  (interfereuce-phenomeuaj,  but  in  other  cases  on  col- 
oring matters  of  various  kinds.  Such  a  coloring  matter  is  the  amorphous  red- 
dish-violet turacin,  which  contains  copper,  and  whose  spectrum  is  very  similar 
to  that  of  oxyhaemoglobin.  Krukenberg  found  a  large  number  of  coloring 
matters  in  birds'  feathers,  namely,  zooerytTirin,  zoofidvin,  iuracoverdin,  zoom- 
bin,  psitiacofulmn,  and  others  which  cannot  be  enumerated  here. 

Tetronerythrin,  so  named  by  Wurm,  is  a  red  amorphous  coloring  matter 
which  is  soluble  in  alcohol  and  ether,  and  which  occurs  in  the  red  warty 
spots  over  the  eyes  of  the  heath-cock  and  the  grouse,  and  which  is  very  widely 
spread  among  the  invertebrates  (Halliburton,  De  Merejkowski,  MacMunn). 
Besides  tetronerythrin  MacMtjnn  found  in  the  shells  of  crabs  and  lobsters  a 
blue  coloring  matter,  cyanocri/stallin,  vfhich  turns  red  with  acids  and  by  boiling 
water.  Hcematoporphyrin,  according  to  MacMunn,  also  occurs  in  the  integu- 
ments of  certain  lower  animals. 

In  addition  to  the  coloring  matters  thus  far  mentioned  a  few  others  found 
in  certain  animals  (though  not  iu  the  skin)  will  be  spoken  of. 

Carminic  acid,  or  the  red  coloring  matter  of  cochineal,  has  the  composition 
CitHisOio.  It  gives  sugar  on  boiling  with  acids,  but  this  does  not  correspond 
with  the  recent  statements  of  Liebermann.  The  beautiful  purple  solution  of 
ammonium  carmiuate  has  two  absorption-bands  between  D  and  E  which  are 
similar  to  those  of  oxyhaemoglobin.  These  bands  lie  nearer  to  ^  and  closer 
together  and  are  less  sharply  defined.  Purple  is  the  evaporated  residue  from 
the  purple-violet  secretion,  caused  by  the  action  of  the  sunlight,  from  the  so- 
called  "  purple  gland  "  of  the  tunic  of  certain  species  of  murex  and  purpura. 
Its  chemical  nature  has  not  been  investigated. 

Among  the  remaining  coloring  matters  found  in  invertebrata  we  may  men- 
tion blue  stentorin,  actiniochrom,  ionellin,  polyperythrin,  pentacrinin,  ante- 
donin,  emstaceorubiti,  janthinin,  and  chlorophyll. 


326  PETSIOLOGICAL   CHEMISTRT. 

Sebum,  when  freshly  secreted,  is  an  oily  semi-fluid  mass  which 
solidifies  on  the  upper  surface  of  the  skin,  forming  a  greasy  coating. 
The  quantity  is  very  different  in  different  persons.  Hoppe-Setler 
has  found  a  body  similar  to  casein,  besides  albumin  and  fat,  in  the 
sebum.  Cholesterin  is  also  found  in  this  fat,  and  in  especially  large 
quantities  in  the  vernix  caseosa.  The  solids  of  the  sebum  consist 
chiefly  of  fat  epithelium-cells  and  protein  bodies;  the  vernix  case- 
osa consists  chiefly  of  fat. 

Cerumen  is  a  mixture  of  the  secretion  of  the  sebaceous  and 
sweat  glands  of  the  cartilaginous  part  of  the  outer  organs  of  hear- 
ing. It  contains  chiefly  soaps  and  fat,  and  besides  these  a  red  sub- 
stance easily  soluble  in  alcohol  and  with  a  sweetish-bitter  taste. 

The  preputial  secretion,  s^negma  jJrcBputii,  contains  chiefly  fat, 
also  cholesterin  and  ammonium  soaps,  which  probably  are  produced 
from  decomposed  urine.  The  hippuric  acid,  benzoic  acid,  and  cal- 
cium oxalate  found  in  the  smegma  of  the  horse  have  probably  the 
same  origin. 

We  may  also  consider  as  a  preputial  secretion  the  castoreum,  which  is 
secreted  by  two  peculiar  glandular  sacks  in  the  prepuce  of  the  beaver.  This 
castoreum  is  a  mixture  of  proteids,  fat,  resins,  traces  of  phenol  (volatile  oil), 
and  a  non-uitrogenized  body,  castorin,  crystallizing  in  four-sided  needles  from 
alcohol,  insoluble  in  cold  water,  but  somewhat  soluble  in  boiling  water,  and 
whose  composition  is  little  known. 

Wool-fat,  or  the  so-called  fat-sweat  of  sheep,  is  a  mixture  of  the  secretion  of 
the  sudoriparous  and  sebaceous  glands.  We  find  in  the  watery  extract  a  large 
quantity  of  potassium  which  is  combined  with  organic  acid,  volatile  and  non- 
volatile fatty  acids,  benzoic  acid,  phenol-sulphuric  acid,  lactic  acid,  malic  acid, 
succinic  acid,  and  others  (Buisine).  The  fat  contains  among  other  bodies 
abundant  quantitiesof  ethers  of  fatty  acids  with  cholesterin  and  isocholesterin. 

Weber  found  that  from  the  glands  of  the  skin  of  a  kangaroo  and  a  dwarf- 
antelope  a  colorless  secretion  was  eliminated  which  in  the  first  case,  when  ex- 
posed to  the  air,  formed  a  red  and  in  the  second  case  a  blue  coloring  matter. 
The  secretion  of  the  coccygeal  glands  of  ducks  and  geese  contains  a  body  sim- 
ilar to  casein,  besides  albumin,  nuclein,  lecithin,  and  fat,  but  no  sugar  (De 
Jonge).  Poisonous  bodies  have  been  found  in  the  secretion  of  the  skin  of  the 
salamander  and  the  toad,  respectively,  samandarin  (Zalesky)  and  bufidin{3oTi,' 
NAKA  and  Casali). 


The  Sweat.  A  disproportionally  large  part  of  the  secretions  of 
the  skin  whose  quantity  amounts  to  about  -gV  of  the  weight  of  the 
body  consists  of  water.  Next  to  the  kidneys  the  skin  is  the  most 
important  means  for  the  elimination  of  water.  As  the  glands  of 
the  skin  and  the  kidneys  stand  near  to  each  other  in  regard  to 


THE  SKIN  AND  ITS  SECRETIONS.  327 

their  functions,  they  may  to  a  certain  extent  act  vicariously  for 
one  another. 

Various  conditions  affect  both  the  character  and  quantity  of  the 
sweat  secreted.  Tlie  secretion  differs  for  different  parts  of  the 
skin,  and  it  has  been  stated  that  tlie  perspirations  of  the  cheek  the 
palm  of  the  hand,  and  under  the  arm  stand  to  each  other  as  100: 
90  :  45.  From  the  unequal  secretion  on  different  parts  of  the  body 
it  follows  tliat  no  results  as  to  the  amount  of  secretion  for  the  en- 
tire surface  of  the  body  can  be  calculated  from  the  amount  secreted 
by  a  small  part  of  the  skin  in  a  given  time.  In  determining  the 
total  amount  a  stronger  secretion  is  as  a  rule  produced,  and  as  the 
glands  can  with  difficulty  work  for  a  long  time  with  the  same  energy, 
it  is  hardly  correct  to  estimate  the  quantity  of  secretion  per  24 
hours  from  a  strong  secretion  enduring  only  a  short  time.  Favre 
obtained  2560  grms.  sweat  in  1^  hours  from  the  entire  surface  of 
the  body  in  a  steam-bath  and  with  abundant  drinking  of  water. 

The  perspiration  obtained  for  investigation  is  never  quite  pure, 
but  contains  cast-off  epidermis-cells,  also  cells  and  fat-globules 
from  the  sebaceous  glands.  Filtered  sweat  is  a  clear,  colorless 
fluid  with  a  salty  taste  and  of  different  odors  from  different  parts 
of  the  body.  The  physiological  reaction  is  acid,  according  to  most 
statements ;  still  after  continuous  secretion  the  sweat  may  be  alka- 
line (Favre  and  Gillibert,  Trumpy  and  Ltjchsinger).  An 
alkaline  reaction  may  also  depend  on  a  decomposition  with  the 
formation  of  ammonia.  According  to  a  few  investigators,  the  phy- 
siological reaction  is  alkaline,  and  an  acid  reaction  depends,  accord- 
ing to  these  investigators,  upon  an  admixture  of  fatty  acids  from 
the  sebum.  Moriggia  found  that  the  sweat  from  herbivora  was 
ordinarily  alkaline,  while  that  from  carnivora  was  generally  acid. 
The  specific  gravity  of  sweat  is  1.003-1.005. 

Perspiration  contains  977.4-995.6  p.  m.,  average  988.2  p.  m., 
water,  and  4.4-22.6  p.  m.,  average  11.80  p.  m.,  solids.  The  organic 
bodies  are  neutral  fats,  cholesterin,  volatile  fatty  acids,  traces  of 
albumin  (according  to  Leclerc  habitually  in  horses  ;  sometimes  in 
man  after  hot  baths,  in  Bright's  disease,  and  after  the  use  of 
pilocarpin),  also  creatinin  (Capranica),  aromatic  oxyacids,  ethereal 
sulphuric  acids  of  phenol  and  sl-aioxyl  (Kast),  but  not  of  indoxyl, 
and  lastly  urea.     The  amount  of  urea,  which  according  to  Funke 


328  PHTSIOLOQICAL   CHEMISTRY. 

is  1.99  p.  m.,  Las  been  more  exactly  determined  in  later  times  by 
Akgutinsky.  In  two  steam-bath  experiments,  in  which  in  the 
course  of  i  and  f  hour  lie  obtained  respectively  225  and  330  c.  c. 
sweat,  he  found  1.61  and  1.24  p.  m.  urea.  In  uraemia,  and  in 
ischuria  in  cholera,  urea  may  be  secreted  in  such  quantities  by  the 
sweat-glands  that  crystals  deposit  upon  the  skin.  The  mineral 
bodies  consist  chiefly  of  sodium  chloride  with  some  potassium 
chloride,  alkali  sulphate,  and  phosphate.  The  relative  amounts  of 
these  in  perspiration  differ  materially  from  the  amounts  in  the 
urine  (Fayee,  Kast).  The  relationship,  according  to  Kast,  is  as 
follows : 


Chlorine 

Phosphate 

Sulphate 

In  perspiration 

1 

0.0015 

0.009 

In  urine 

1 

0.1320 

0.397 

Kast  found  that  the  proportion  of  ethereal  sulphuric  acid  to 
the  sulphate  sulphuric  in  sweat  was  1:12.  After  the  administra- 
tion of  aromatic  substances  the  ethereal  sulphuric  acid  does  not 
increase  to  the  same  extent  in  the  sweat  as  in  the  urine  (see  Chap. 
XIV). 

Sugar  may  pass  into  the  sweat  in  diabetes,  but  the  passage  of  the  bile-col- 
oring matters  has  not  been  positively  shown  in  this  secretion.  Benzoic  acid, 
succinic  acid,  tartaric  acid,  iodine,  arsenic,  mercuric  chloride,  and  quinine  pass 
into  the  sweat.  Uric  acid  has  also  been  found  in  the  sweat  in  gout,  and 
cystin  in  cystinnra. 

Chromhidrosis  has  been  called  the  secretion  of  colored  sweat.  Sometimes 
sweat  has  been  observed  to  be  colored  blue  by  indigo  (Bizio),  by  pyocyanin 
(FoRDos),  or  by  ferro-phosphate  (Kollmann).  True  blood-sweat,  in  which 
blood-corpuscles  exude  from  the  openings  of  the  glands,  has  also  been  ob- 
served. 

The  exchange  of  gas  through  the  shin  in  man  is  of  very  little 
importance  compared  to  the  exchange  of  gas  by  the  lungs.  The 
absorption  of  oxygen  by  the  skin,  which  was  first  shown  by  Keg- 
NAULT  and  Eeiset,  is  very  small.  The  quantity  of  carbon  dioxide 
eliminated  by  the  skin  increases  with  the  rise  of  {emperature 
(AuBERT,  RoHRiG,  EuBHsTi,  and  EoisrcHi).  It  is  also  greater  in 
light  than  in  darkness.  It  is  greater  during  digestion  than  when 
fasting,  and  greater  after  a  vegetable  than  after  an  animal  diet 
(FuBiNi  and  Ronchi).  According  to  ScHAKLiJSfG  it  is  10  grms., 
and  according  to  Aitbeet  3.9  grms.,  in  24  hours.    In  certain  ani- 


THE  SKIN  AND  ITS  SECRETIONS.  329 

mals,  as  in  frogs,  the  exchange  of  gas  through  the  skin  is  of  great 
importance. 

As  the  exchange  of  gas  through  the  skin  in  man  and  mammalia 
is  very  small,  it  follows  that  the  injurious  and  dangerous  effects 
caused  by  covering  the  skin  with  varnish,  oil,  or  the  like,  can  hardly 
depend  on  a  prevented  exchange  of  gas.  After  varnishing  the  skin 
there  is  a  considerable  loss  of  heat,  and  the  animal  quickly  dies. 
If  the  animal,  on  the  contrary,  be  guarded  from  this  loss  of  heat,  it 
may  be  saved,  or  kept  at  least  alive,  for  a  longer  time.  This  effect 
was  supposed  to  be  due  to  a  poisoning  caused  by  a  retention  of  one 
or  more  substances  of  the  perspiration  {pei'spirahile  retentum),  ac- 
companied by  fever  and  increased  loss  of  heat  through  the  skin; 
but  this  statement  has  not  been  substantiated.  This  phenomenon 
seems  to  be  due  to  other  causes,  and  at  least  in  certain  animals 
(rabbits)  death  seems  to  ensue  from  the  paralyzation  of  the  vaso- 
motor nerves.  In  anastomosis  the  loss  of  heat  through  the  skin 
seems  to  be  increased  to  such  an  extent  that  the  animal  dies  from 
the  lowered  temperature. 


CHAPTER  XIV. 
THE   URINE. 

The  urine  is  the  most  important  excretion  of  the  animal  or- 
ganism; it  is  the  means  of  eliminating  the  nitrogenized  products 
of  exchange,  also  the  water  and  the  soluble  mineral  substances; 
and  in  many  cases  it  furnishes  important  data  relative  to  the 
exchange  of  material;  quantitatively,  by  its  variation,  and  quaUta- 
tively  by  the  appearance  of  foreign  bodies  in  the  excretion.  Also 
in  many  cases  we  are  able  from  the  chemical  or  morphological 
constituents  which  the  urine  abstracts  from  the  kidneys,  ureters, 
bladder,  and  urethra  to  Judge  of  the  condition  of  these  organs; 
and  lastly,  urinary  analysis  afEords  an  excellent  means  of  deciding 
the  question  how  certain  medicines  or  other  foreign  substances 
introduced  into  the  organism  are  absorbed  and  chemically  changed. 
Urinary  analysis  has  furnished  very  important  particulars  espe- 
cially relative  to  the  last-mentioned  question  in  regard  to  the 
nature  of  the  chemical  processes  taking  place  within  the  organism, 
and  it  is  therefore  not  only  an  important  aid  in  diagnosis  to  the  • 
physician,  but  it  is  also  of  the  greatest  importance  to  the  toxicol- 
ogist  and  the  physiological  chemist. 

In  studying  the  secretions  and  excretions  the  relationship  must 
be  sought  between  the  chemical  structure  of  the  secreting  organ 
and  the  chemical  composition  of  its  secreted  products.  Investiga- 
tions with  respect  to  the  kidneys  and  the  urine  have  led  to  very 
few  results  from  this  standpoint.  Although  the  anatomical  rela- 
tion of  the  kidneys  has  been  carefully  studied,  their  chemical  com- 
position has  not  been  the  subject  of  thorough  analytical  research. 
In  cases  in  which  a  chemical  investigation  of  the  kidneys  has  been 
undertaken,  it  has  only  been  in  general  on  the  organ  as  such,  and 
not  on  the  different  anatomical  parts.     An   enumeration  of  the 

330 


THE  URINE.  331 

chemical  constituents  of  the  kidneys  known  at  the  present  time 
can,  therefore,  only  have  a  secondary  value. 

In  the  kidneys  we  find  albuminous  bodies  of  different  kinds, 
namely,  globulin,  albumin,  and  nucleoalbumin,  also  a  gelatine- 
forming  and  elastic  substance,  and  lastly  a  body  similar  to  muciii. 
The  question  as  to  whether  pure  mucin  really  exists  in  the  kidneys 
has  not  been  decided.  The  body  similar  to  mucin,  which  is  a 
nucleoalbumin  and  which  gives  no  reducible  substance  when 
boiled  with  acids  (Lonxbekg),  belongs  chiefly  to  the  papillse,  while 
the  nucleoalbumin  dissimilar  to  mucin  belongs  to  the  cortical  sub- 
stance. Fat  only  occurs  in  very  small  amounts  in  the  cells  of  the 
tortuous  urinary  passages.  Among  the  extractive  bodies  of  the 
kidneys  we  find  xanthin  bodies,  also  adenin  (Kroxeckek),  urea, 
and  traces  of  iiric  acid,  glycogen,  leucin,  inosit,  taurin,  and  cystin 
(in  ox-kidneys).  The  quantitative  analyses  of  the  kidneys  thus  far 
made  possess  little  interest.  The  quantity  of  water  in  human  kid- 
neys is  82S.4  p.  m.  according  to  Feeeichs,  and  834.5  p.  m.  according 

to  VOLKMAXX. 

The  fluid  collected  under  pathological  conditions,  as  in  hydronephrosis,  is 
thin  with  a  variable  but  generally  low  specific  gravity.  Usually  it  is  straw- 
yellow  or  paler  in  color,  and  sometimes  colorless.  Most  frequently  it  is  clear, 
or  only  faintly  cloudy  from  white  blood-corpuscles  and  epithelium-cells  ;  in  a 
few  cases  it  is  so  rich  in  form-elements  that  it  appears  like  pus.  Albumin 
occurs  generally  only  in  small  amounts  ;  sometimes  it  is  entirely  absent,  and 
in  a  few  rare  cases  the  amount  is  nearly  as  large  as  in  the  blood-serum.  Urea 
occui"s  sometimes  in  considerable  amounts  when  the  parenchyma  of  the 
kidneys  is  onlj'  in  part  atrophied  ;  in  complete  atrophy  the  urea  may  be 
entirely  absent. 

I.  Physical  Properties  of  Urine. 

Consistency,  transparency,  odor,  and  taste  of  urine.  Urine  is 
under  physiological  conditions  a  thin  liquid  and  gives,  when 
shaken  with  air,  a  froth  which  quickly  subsides.  Human  urine  or 
urine  from  carnivora,  which  is  habitually  acid,  appears  clear  and 
transparent,  often  faintly  fluorescent  immediately  after  voiding. 
"When  allowed  to  stand  for  a  little  while  human  urine  shows  a  light 
cloud  {nubecula)  which  consists  of  the  so-called  ** mucus"  and 
generally  also  contains  a  few  epithelium-cells,  mucus-corpuscles, 
and  urate-granules.  The  presence  of  a  larger  quantity  of  urates 
(uric-acid  salts)   renders    the   urine   cloudy,  and    a    clay-yellow. 


332  PHYSIOLOGICAL   CHEMISTRY. 

yellowish-brown,  rose-colored,  or  often  brick-red  precipitate  {sedi- 
mentum  lateritium)  settles  on  cooling  because  of  the  greater  insolu- 
bility of  the  urates  at  the  ordinary  temperature  than  at  the  temper- 
ature of  the  body.  This  cloudiness  disappears  on  gently  warming. 
In  new-born  infants  the  cloudiness  of  the  urine  during  the  first 
4-5  days  is  due  to  epithelium,  mucus-corpuscles,  uric  acid,  and 
urates.  The  urine  of  herbivora,  which  is  habitually  neutral  or 
alkaline  in  reaction,  is  very  cloudy  on  account  of  the  carbonates  of 
the  alkaline  earths  present.  Human  urine  may  sometimes  be 
alkaline  under  physiological  conditions.  In  this  case  it  is  made 
cloudy  by  the  earthy  phosphates,  and  this  cloudiness  does  not  dis- 
appear on  warming,  differing  in  this  respect  from  the  sedimeiitum 
lateritium.  Urine  has  a  salty  and  faintly-bitter  taste  produced  by 
sodium  chloride  and  urea.  The  odor  of  urine  is  peculiarly  aro- 
matic; the  bodies  which  produce  this  odor  are  unknown. 

The  color  of  urine  is  normally  pale  yellow  when  the  specific 
gravity  is  1.020.  The  color  otherwise  depends  on  the  concentration 
of  the  urine  and  varies  from  pale  straw-yellow,  when  the  urine 
contains  small  amounts  of  solids,  to  a  dark  reddish  yellow  or  reddish 
brown  in  stronger  concentration.  As  a  rule,  the  intensity  of  the 
color  corresponds  to  the  concentration,  but  under  pathological 
conditions  exceptions  occur,  and  such  an  exception  is  found  in 
diabetic  urine,  which  contains  a  large  amount  of  solids  and  has  a 
high  specific  gravity  and  a  pale  yellow  color. 

The  reaction  of  urine  depends  essentially  upon  the  composition 
of  the  food.  The  carnivora  void  an  acid,  the  herbivora  a  neutral 
or  alkaline,  urine.  If  a  carnivora  is  put  on  a  vegetable  diet,  its 
urine  may  become  less  acid  or  neutral,  while  the  reverse  occurs 
when  an  herbivora  is  starved,  that  is,  when  it  lives  upon  its  own 
flesh,  as  then  the  urine  voided  is  acid. 

The  urine  of  a  healthy  man  on  a  mixed  diet  has  an  acid  reaction, 
and  the  sum  of  the  acid  equivalents  is  greater  than  the  sum  of  the 
base  equivalents.  This  depends  on  the  fact  that  in  the  physiolog- 
ical burning  of  neutral  substances  (proteids  and  others)  within 
the  organism  acids  are  produced,  chiefly  sulphuric  acid,  but  also 
phosphoric  and  organic  acids,  such  as  hippuric,  uric,  and  oxalic 
acid,  also  aromatic  oxyacids  and  others.  From  this  it  follows  that 
the  acid  reaction  is  not  due  to  one  acid  alone.     We  do  not  know  to 


THE  URINE.  333 

what  extent  any  one  acid  takes  part  in  the  acid  reaction;  but  as  the 
sum  of  the  base  equivalents  is  greater  than,  or  at  least  the  same  as,  the 
sum  of  the  inorganic  acid  equivalents,  the  acid  reaction  must  be 
due  in  greatest  part  to  organic  acids  or  acid  salts.  It  is  generally 
considered  that  the  acid  reaction  of  human  urine  is  caused  by 
double-acid  alkali-phosphate  (monophosphate).  The  amount  of 
acid-reacting  bodies  or  combinations  eliminated  by  the  urine  in  24 
hours,  when  calculated  as  oxalic  acid  or  hydrochloric  acid,  is  re- 
spectively 2-4  and  1.15-2.3  grms.  (Vogel). 

The  composition  of  the  food  is  not  the  only  influence  which 
affects  the  degree  of  acidity  of  human  iirine.  For  example,  after 
taking  food,  at  the  beginning  of  digestion,  when  a  larger  amount  of 
gastric  juice  containing  hydrochloric  acid  is  secreted,  the  urine  may 
be  neutral  or  even  alkaline.  The  greatest  amount  of  acid  or  acid- 
salts  per  hour  is  secreted,  according  to  Vogel,  during  the  night, 
while  according  to  Hoffmakx,  it  is  in  the  afternoon.  The  smallest 
amount  is  voided,  according  to  HoffmajSTN"  during  the  night,  but 
QuixcKE  claims  that  it  is  in  the  morning.  It  has  not  infrequently 
been  observed  that  perfectly  healthy  persons  in  the  morning  void  a 
neutral  or  alkaline  urine  which  is  cloudy  from  earthy  phosphates. 
The  effect  of  muscular  activity  on  the  acidity  of  urine  is  yet 
undetermined.  According  to  Hoffmann  and  Rijstgstedt,  mus- 
cular work  raises  the  degree  of  acidity,  but  Aducco  claims  that  it 
decreases  it.  Abundant  perspiration  reduces  the  acidity  (Hoff- 
mann). 

In  man  and  carnivora  it  seems  that  the  degree  of  acidity  of 
the  urine  cannot  be  increased  above  a  certain  point,  even  though 
mineral  acids  or  organic  acids  which  are  burnt  up  with  difficulty 
are  taken  in  large  quantities.  When  the  supply  of  carbonates  of 
the  fixed  alkalies  stored  up  in  the  organism  for  this  purpose  is  not 
sufficient  to  combine  with  the  excess  of  acid,  then  ammonia  is  split 
from  the  proteids  or  their  decomposition  products,  and  the  excess 
of  acid  combines  therewith,  forming  ammonium-salts  which  pass 
into  the  urine.  In  herbivora  this  splitting  of  ammonia  and  forma- 
tion of  ammonia-salts  does  not  seem  to  take  place,  and  the  herbiv- 
ora therefore  soon  die  when  acids  are  given.  Nevertheless,  the 
degree  of  acidity  of  human  urine  may  be  easily  diminished  so  that 
the  reaction  is  neutral  or  alkaline.     This  occurs  after  the  taking  of 


334  PHYSIOLOGICAL  CHEMISTRY. 

carbonates  of  the  fixed  alkalies  or  of  such  salts  of  vegetable  acids — 
tartaric  acid,  citric-acid,  and  malic-acid  salts — as  are  easily  burnt 
into  carbonates  in  the  organism.  Under  pathological  conditions,  as 
in  the  absorption  of  alkaline  transudations,  the  urine  may  become 
alkaline  (Quincke). 

The  degree  of  acidity  cannot  be  determined  by  the  ordinary  acidi- 
metric  process,  since  the  urine  contains  di-hydrogen  phosphate, 
MHgPOi,  besides  hydrogen  di-phosphate  MgHPO^.  In  tlie  titra- 
tion the  di-hydrogen  phosphate  is  changed  gradually  into  M2HP0i, 
and  we  obtain  at  a  certain  point  a  mixture  of  the  two  phosphates  in 
variable  proportions,  which  mixture  is  not  neutral  but  amphoteric. 
Since  it  is  generally  admitted  that  the  acid  reaction  of  urine  is  due 
to  the  di-hydrogen  phosphate,  it  is  therefore  best  to  express  the 
degree  of  acidity  by  the  amount  of  di-hydrogen  phosphate  present. 

If  we  wish  to  calculate  the  degree  of  acidity  of  the  urine 
as  di-hydrogen  phosphate  or,  still  more  simply,  as  phosphoric 
anhydride,  PaOg,  contained  in  this  salt,  the  titration  is  performed 
according  to  the  method  of  Maly  and  Hoffmann,  which  is  as  fol- 
lows :  The  urine  (100-200  c,  c.)  is  treated  with  an  exactly-measured 
quantity  of  5  normal  caustic-soda  solution,  which  is  more  than  suf- 
ficient to  convert  all  the  phosphate  into  basic  phosphate,  or,  in  other 
words,  enough  to  make  the  urine  strongly  alkaline.  Then  an 
approximate  f  normal  BaClj  solution  (142.8  grms.  BaCl2,2H02in 
a  litre)  is  added  until  no  further  precipitate  is  formed.  By  this 
means  all  the  phosphoric  acid  is  precipitated  from  the  urine.  Filter 
through  a  dry  filter,  measure  a  quantity  corresponding  to  50  or 
100  c.  0.  of  the  original  urine  from  the  filtrate,  and  titrate  with 
^  normal  sulphuric  acid  until  a  neutral  reaction  is  obtained,  using 
litmus-paper  as  an  indicator.  If  the  amount  found  by  this  titration 
be  subtracted  from  the  original  amount  of  caustic  soda  added  to 
this  volume  of  urine,  the  difference  is  the  amount  of  caustic  soda 
necessary  to  convert  the  existing  di-hydrogen  and  hydrogen  di-phos- 
phates  into  normal  phosphate.  If  we  designate  this  by  «,'and  the 
quantity  of  total  P2O5  in  milligrammes  in  the  same  quantity  of 
urine,  as  determined  by  a  method  which  will  be  described  later,  by  g, 
then  we  obtain  the  quantity  of  P2O5  in  milligrammes  in  the  di-hy- 
drogen phosphate  s  by  the  following  formula:  s  =  17.75  a  —  g 
(Huppeet). 

If,  for  example,  in  a  case  in  which  the  conversion  of  both  phos- 
phates into  normal  phosphate  in  100  c.c.  of  the  urine  required  20  c.c. 
caustic  soda,  while  the  total  quantity  of  P2O5  in  100  c.c,  urine  was 
275  milligrammes,  then :  s  =  17.75  X  20  —  275  =  80  milligrammes. 
The  quantity  of  P2O5  as  simple  acid  phosphate  was  therefore  195 
milligrammes. 


THE  URINE.  •  335 

A  ui-ine  with  an  alkaline  reaction  caused  by  fixed  alkalies  has  a 
very  different  diagnostic  value  than  one  whose  alkaline  reaction  is 
caused  by  the  presence  of  ammonium  carbonate.  In  the  latter  case 
we  have  to  deal  with  a  decomposition  of  the  urea  of  the  urine  by 
the  action  of  micro-organisms. 

If  we  wish  to  determine  whether  the  alkaline  reaction  of  the 
urine  is  due  to  ammonia  or  fixed  alkalies,  we  dip  a  piece  of  red 
litmus-paper  into  the  urine  and  allow  it  to  dry  exposed  to  the  air  or 
to  a  gentle  heat.  If  the  alkaline  reaction  is  due  to  ammonia,  the 
paper  becomes  red  again  ;  but  if  it  is  caused  by  fixed  alkalies,  it 
remains  blue. 

The  specific  gravity  of  urine,  which  is  dependent  upon  the 
relationship  existing  between  the  quantity  of  water  secreted  and 
the  solid  uriuary  constituents,  especially  the  urea  and  sodium 
chloride,  may  vary  considerably,  but  is  generally  1.017-1.020. 
After  drinking  large  quantities  of  water  it  may  fall  to  1.002,  while 
after  profuse  perspiration  or  after  drinking  very  little  water  it  may 
rise  to  1.035-1.040.  In  new-born  infants  the  specific  gravity  is  low, 
1.007-1.005.  The  determination  of  the  specific  gravity  is  an  im- 
portant means  of  learning  the  average  amount  of  solids  elimi- 
nated from  the  organism  with  the  urine,  and  on  this  account  the 
determination  becomes  of  true  value  only  when  at  the  same  time  the 
quantity  of  urine  voided  in  a  given  time  is  determined.  The  dif- 
ferent portions  of  urine  voided  in  the  course  of  the  24  hours  are 
collected,  mixed  together,  the  total  quantity  measured,  and  then 
the  specific  gravity  taken. 

The  determiiiation  of  the  specific  gravity  is  most  accurately  ob- 
tained with  the  pyknometer.  For  ordinary  cases  the  specific  grav- 
ity may  be  determined  with  sufficient  accuracy  by  means  of 
areometers.  The  areometers  found  in  the  trade,  or  nrinometers, 
are  graduated  from  1.000  to  1.040;  for  exact  observations  it  is  better 
to  use  two  nrinometers,  one  graduated  from  1.000  to  1.020,  and  the 
other  from  1.020  to  1.040.  A  special  uriuometer  is  that  of  Heller, 
which  is  graduated  according  to  Baume's  scale,  from  0  to  8,  Each 
degree  corresponds  to  7  degrees  of  the  ordinary  urinometer,  and  as 
the  zero-point  of  Heller's  urinometer  corresponds  to  the  figure 
1000,  then  the  1,  1.5,  2,  2.5,  3,  etc.,  degrees  of  Heller's  urinometer 
correspond  to  1.007,  1.0105,  1.014,  1.0175,  1.024,  etc.,  of  the  ordi- 
nary specific  gravity. 


336  PHYSIOLOGICAL   CHEMISTRY. 

To  determine  the  specific  gravity  of  urine,  if  necessary  filter 
the  ui'ine,  or  if  it  contains  a  urate  sediment,  first  dissolve  it  by  gentle 
heat,  then  pour  the  clear  urine  into  a  dry  cylinder,  avoiding  the 
formation  of  froth.  Air-bubbles  or  froth,  when  present,  must  be 
removed  with  a  glass  rod  or  filter-paper.  The  cylinder,  which  must 
be  about  |  full,  must  be  wide  enough  to  allow  the  urinometer  to 
swim  freely  in  the  liquid  without  touching  the  sides.  The  cylinder 
and  urinometer  should  both  be  dry  or  previously  washed  with  the 
urine.  On  reading,  the  eye  is  brought  on  a  level  with  the  lower 
meniscus — which  occurs  when  the  surface  of  the  liquid  and  the 
lower  limb  of  the  meniscus  coincide  ;  the  reading  is  then  made 
'from  the  point  where  this  curved  line  cuts  the  scale  of  the 
urinometer.  If  the  eye  is  not  in  the  same  horizontal  plane  with  the 
convex  line  of  the  meniscus,  but  is  too  high  or  too  low,  the  surface 
of  the  liquid  assumes  the  shape  of  an  ellipse,  and  the  reading  in 
this  position  is  incorrect.  Before  reading  press  the  urinometer 
gently  down  into  the  liquid  and  then  allow  it  to  rise,  and  wait  until 
it  is  at  rest. 

If  the  quantity  of  urine  at  disposal  is  not  sufficient  to  fill  the 
cylinder  to  the  proper  height  it  may  be  diluted,  according  to  circum- 
stances, with  an  equal  volume  or  several  volumes  of  water.  This  does 
not  give  quite  accurate  results,  and  with  small  quantities  of  urine 
it  is  best  to  determine  the  specific  gravity  by  means  of  the  pyk- 
nometer.  ^  ^ 

Each  urinometer  is  graduated  for  a  certain  temperature,  which 
is  marked  on  the  instrument,  or  at  least  on  the  best.  If  the  urine 
is  not  at  the  proper  temperature,  the  following  corrections  must  be 
made:  For  every  three  degrees  above  the  normal  temperature  one 
unit  of  the  last  order  is  added  to  the  reading,  and  for  every  three 
degrees  below  the  normal  temperature  one  unit  (as  above)  is  sub- 
tracted from  the  specific  gravity  observed.  For  example,  when  a 
urinometer  graduated  for  +  15°  0.  shows  a  specific  gravity  of  1.017 
at  4-  24°  C,  then  the  specific  gravity  at  +  15°  C.  =  1.017  +  0.003 
=  1.030. 

II.  Organic  Physiological  Constituents  of  the  Urine. 

Urea,  Ur,  which  is  ordinarily  considered  as  carbamid,  CO(NH2)2, 
may  be  synthetically  prepared  in  several  different  ways,  namely, 
from  carbonyl-chloride,  or  carbonic-acid  ethyl-ether  and  ammonia, 
COCI2  +  2NH3  =  CO(NH2)2  +  2HC1,  or  {G^,),.0,.QO  +  2NH3  = 
2(02H5.0H)  +  CO(NH2)2;  by  the  metameric  decomposition  of 
ammonium  cyanate,  (NH,).O.CN  ==  CO(NH2)2  (Wohler,  1828); 
and  in  many  other  ways.     It  is  also  formed  by  the  decomposition 


THE  URINE.  337 

or  oxidation  of  certain  bodies  found  in  the  animal  organism,  such 
as  creatin  and  uric  acid. 

Urea  is  found  most  abundant  in  the  urine  of  carnivora  and  man, 
but  in  smaller  quantities  in  that  of  herbivora.  The  quantity  in 
human  urine  is  ordinarily  20-30  p.  m.  It  has  also  been  found  in 
the  urine  of  certain  birds  and  amphibians.  Urea  occurs  in  the  per- 
spiration in  small  quantities,  about  2  p.  m.,  and  as  traces  in  the 
blood  and  in  most  of  the  animal  fluids.  It  is  also  found  in  certain 
tissues  and  organs,  especially  in  the  liver  (in  mammalia)  and  the 
spleen,  but  not  in  the  muscles.  Under  pathological  conditions,  as 
in  obstructed  secretion  of  urine,  the  urea  in  the  animal  fluids  and 
tissues  may  increase  to  a  considerable  amount.  Under  these  cir- 
cumstances it  may  also  occur  in  the  muscles. 

The  quantity  of  urea  which  is  voided  in  24  hours  on  a  mixed 
diet  is  in  a  grown  man  about  30  grammes,  for  women  somewhat 
less.  Children  void  absolutely  less,  but  relative  to  their  body- 
weight  the  excretion  is  larger  than  in  grown  persons.  The  physio- 
logical significance  of  urea  lies  in  the  fact  that  this  body  forms  in 
man  and  carnivora,  from  a  quantitative  standpoint  the  most  im- 
portant nitrogenized  final  product  of  the  metabolism  of  proteid 
bodies.  On  this  account  the  elimination  of  urea  varies  to  a  great 
extent  with  the  amount  of  proteid  transformed,  and  above  all  with 
the  quantity  of  absorbable  proteids  in  the  food  taken.  The  elimina- 
tion of  urea  is  greatest  after  an  exclusive  meat  diet,  and  lowest, 
indeed  less  than  during  starvation,  after  the  consumption  of  bodies 
free  from  nitrogen,  for  these  diminish  the  metabolizatiou  of  the 
proteids  of  the  body. 

If  the  consumption  of  the  proteids  of  the  body  is  increased,  then 
the  elimination  of  urea  is  correspondingly  increased.  This  is  found 
to  a  rather  high  degree  in  certain  diseases  with  fever;  also,  though 
to  a  less  extent,  after  taking  common  salt  or  after  abundant  drink- 
ing of  water  (Voix).  The  elimination  of  urea  is  also  somewhat 
increased  by  several  medicines;  and  lastly  it  is  also  increased  after 
poisoning  with  arsenic,  antimony,  and  phosphorus,  by  the  diminished 
supply  of  oxygen — as  in  severe  and  continuous  dyspnoea — poisoning 
with  carbon  monoxide,  hemorrhage,  etc.  In  these  cases  an  exact 
difference  has  not  always  been  made  between  the  urea  and  the  total 
quantity  of  nitrogen  in  the  urine,  and  it  is  just  this  last  which  is 


338  PHYSIOLOGICAL   CHEMISTUT. 

often  tlie  cause  of  the  increase  found  in  these  cases.  The  amount 
of  nitrogen  contained  in  the  urea  does  not  correspond  with  the 
total  amount  of  nitrogen  in  the  urine,  since,  as  Pfluger  has  shown, 
the  amount  of  nitrogen  which  under  physiological  conditions  occurs 
combined  with  other  combinations  than  urea  is,  on  an  average, 
13.4^,  sometimes  indeed  16^,  of  the  total  nitrogen.  In  disease  this 
relationship  may  be  essentially  changed  and,  as  an  example,  in 
a  case  of  phosphorus  poisoning  Fraeistkel  observed  that  the 
amount  of  nitrogen  contained  in  the  urea  was  less  than  one  half 
of  the  total  amount  of  nitrogen  in  the  urine. 

A  diminished  elimination  of  urea  occurs  in  a  reduced  consump- 
tion of  proteids,  and  also — a  fact  which  is  of  interest  in  regard  to 
the  importance  of  the  liver  in  the  formation  of  urea — in  certain 
diseases  of  the  liver,  as  in  acute  yellow  atrophy  and  sometimes  in 
interstitial  cirrhosis.  Under  these  conditions  the  amount  of  ammo- 
nia in  the  urine  as  compared  to  the  urea  may  be  increased  (Hal- 
LEEVORDEisr,  Stadelmazstn).  In  diseases  of  the  kidneys  which 
disturb  or  destroy  the  integrity  of  the  epithelium  of  the  tortuous 
urinary  passage  the  elimination  of  urea  is  considerably  diminished. 

Formation  of  urea  in  the  organism.  The  experiments  to  produce 
urea  directly  from  the  proteids  by  oxidation  have  not  led  to  any 
positive  results.  We  often  obtain  amido-acids  as  decomposition 
products  of  albumin  (see  page  17),  and  we  therefore  conclude  that 
the  amido-acids  are  intermediate  steps  in  the  formation  of  urea 
from  albumin.  It  has  also  been  shown  that  leucin  and  glycocoll 
(ScHULTZEN  and  Nencki,  Salkowski),  and  asparaginic  acid  (v. 
Knieriem)  may  be  transformed  into  urea  within  the  organism. 
The  nature  of  the  chemical  processes  by  which  these  transforma- 
tions are  effected  is  unknown.  Many  other  ways  for  the  formation 
of  urea  have  been  suggested,  but  the  only  one  which  has  been 
demonstrated  is  the  formation  from  ammonium  carbonate  in  the 
liver.  After  the  researches  of  v.  Knieriem,  Salkowski,  Feder, 
MuNCK,  ScHMiEDEBERG  and  WALTER,  aud  Hallervorden  had 
shown  that  ammonium  carbonate,  or  such  ammonium-salts  as  are 
burnt  up  in  the  system  into  carbonate,  is  converted  into  urea  in  the 
body  of  carnivora  and  herbivora,  v.  Schroder  furnished  a  decisive 
proof  of  the  formation  of  urea  from  ammonium  carbonate  in  the 
liver  of  mammalia.     By  passing  blood  which  had  been  treated  with 


THE  UEINE.  339 

ammonium  carbonate  or  ammonium  formate  through  a  dog's  liver, 
he  found  that  a  considerable  formation  of  urea  took  place.  The 
very  careful  observations  of  Salomon  confirm  this,  and  also  the 
above-mentioned  decrease  of  urea  and  increase  of  ammonia  in  the 
urine  in  certain  diseases  of  the  liver. 

It  cannot  be  denied  that  the  formation  of  urea  in  the  liver  is  of 
great  physiological  importance ;  but  still  it  does  not  follow  that  all 
the  urea  has  its  origin  in  this  organ.  The  possibility  of  a  formation 
of  urea  from  creatin  or  xanthin  bodies  is  not  to  be  rejected  without 
further  inquiry,  and  other  possibilities  as  to  its  formation  are  con- 
ceivable. 

The  question  in  which  organ  urea  is  formed  has  been  the 
subject  of  much  discussion.  From  the  researches  of  numerous 
investigators,  Prevost  and  Dumas,  Meissner,  Voit,  Grehant, 
GscHEiDLEN,  Salkowski,  and  V.  Schroder,  it  has  been  found  that 
the  extirpation  of  the  kidneys  causes  a  considerable  increase  in 
the  quantity  of  urea  in  the  blood.  The  kidneys,  therefore,  although 
they  may  produce  urea  generally,  are  not  the  only  organs  which 
produce  it.  By  experiments  performed  on  the  removed  kidneys, 
which  were  analogous  to  the  above-mentioned  experiments  on  the 
removed  liver,  v.  Schroder  has  shown  that  neither  the  kidneys 
nor  the  muscles  nor  the  remaining  tissues  of  the  lower  extremities 
of  the  dog  have  the  property  of  forming  urea  from  ammonium  car- 
bonate. The  only  organ  in  which  a  formation  of  urea  has  been 
proved  with  certainty,  thus  far,  is  the  liver,  but  this  does  not  ex- 
clude the  possibility  that  urea  may  also  be  formed  in  other  organs, 
perhaps  from  other  material  than  ammonium  carbonate  and  in 
other  ways. 

Properties  and  Reactions  of  Urea.  Urea  crystallizes  in  needles 
or  in  long,  colorless,  four-sided,  often  hollow,  anhydrous  rhombic 
prisms.  It  has  a  neutral  reaction  and  produces  a  cooling  sensation 
on  the  tongue  like  saltpetre.  It  melts  at  130°-132°  C,  but  decom- 
poses already  at  about  100°  C.  At  ordinary  temperatures  it  dis- 
solves in  equal  weight  of  water  and  in  five  parts  alcohol;  it  requires 
one  part  boiling  alcohol  for  solution;  it  is  sparingly  soluble  in 
ether.  If  urea  in  substance  is  heated  in  a  test-tube  it  melts,  de- 
composes, gives  off  ammonia,  and  leaves  finally  a  non-transparent 
.white  residue  which,  among  other  substances,  contains  biuret  and 


340  PHYSIOLOGICAL  CHEMISTRT. 

which  dissolves  in  water,  giving  a  beautiful  reddish-violet  liquid 
with  copper  sulphate  and  alkali  {biuret  reaction).  On  heating  with 
baryta-water  or  caustic  alkali,  urea  splits  into  carbon  dioxide  and 
ammonia  with  the  addition  of  water  ;  this  also  takes  place  by  the 
action  of  micro-organisms,  which  produces  the  so-called  alkaline 
fermentation  of  urine.  The  same  decomposition  is  produced  when 
urea  is  heated  with  concentrated  sulphuric  acid.  An  alkaline  solu- 
tion of  sodium  hypobromite  decomposes  urea  into  nitrogen,  carbon 
dioxide,  and  water  according  to  the  equation 

CON2H,  +  SNaOBr  =  3NaBr  +  CO^  +2H2O  +  Ng. 

Urea  forms  with  many  acids  crystalline  combinations.  Among- 
these  the  one  with  nitric  acid  and  the  one  with  oxalic  acid  are  the 
most  important. 

Urea  Niteate,  CO(KH2)2.H]Sr03.  This  combination  on  crys- 
tallizing quickly  forms  thin  rhombic  or  six-sided,  overlapping 
tiles,  colorless  plates,  whose  point  has  an  angle  of  82°.  On  slowly 
crystallizing,  larger  and  thicker  rhombic  pillars  or  plates  are  ob- 
tained. This  combination  is  rather  easily  soluble  in  pure  water, 
but  is  considerably  less  soluble  in  water  containing  nitric  acid;  it 
may  be  obtained  by  treating  a  concentrated  solution  of  urea  with 
an  excess  of  strong  nitric  acid  free  from  nitrous  acid.  On  heating- 
this  combination  it  volatilizes  without  leaving  a  residue. 

This  compound  may  be  employed  with  advantage  in  detecting  small 
amounts  of  urea.  A  drop  of  the  concentrated  solution  is  placed  on  a  micro- 
scope-slide and  the  cover-glass  placed  upon  it  ;  a  drop  of  nitric  acid  is  then 
placed  on  the  side  of  the  cover-glass  and  allowed  to  flow  under.  The  forma- 
tion of  crystals  begins  where  the  solution  and  the  nitric  acid  meet.  Alkali 
nitrates  may  crystallize  very  similarly  to  urea  nitrate  when  they  are  con- 
taminated with  other  bodies  ;  therefore,  in  testing  for  urea,  the  crystals  must 
be  identified  as  urea  nitrate  by  heating  and  by  other  means. 

Ueea  Oxalate,  ^.GOi^^^iiRzG^Ot.  This  compound  is  more 
sparingly  soluble  in  water  than  the  nitric-acid  compound.  It  is 
obtained  in  rhombic  or  six-sided  prisms  or  plates  on  adding  a 
saturated  oxalic-acid  solution  to  a  concentrated  solution  of  urea. 

Urea  also  forms  combinations  with  mercuric  nitrate  in  variable 
proportions.  If  a  very  faintly-acid  mercuric-nitrate  solution  is 
added  to  a  two-per-cent  solution  of  urea,  and  the  mixture  carefully 
neutralized,  a  combination  is  obtained  of  a  constant  composition 


TEE  URINE.  341 

which  contains  for  every  10  parts  of  urea  7.3  parts  mercuric  oxide. 
This  compound  serves  as  the  basis  of  Liebig's  titration  method. 
Urea  combines  also  with  salts,  forming  mostly  crystallizable  combi- 
nations, as,  for  instance,  with  sodium  chloride,  with  the  chlorides  of 
the  heavy  metals,  etc.  An  alkaline  but  not  a  neutral  solution  of 
urea  is  precipitated  with  mercuric  chloride. 

The  method  of  preparing  urea  from  urine  is  chiefly  as  follows  : 
Concentrate  the  urine,  which  has  been  faintly  acidified  with  sul- 
phuric acid,  at  a  low  temperature,  add  an  excess  of  nitric  acid,  at 
the  same  time  keeping  the  mixture  cool,  press  the  precipitate  well, 
decompose  it  iu  water  with  freshly-precipitated  barium  carbonate, 
dry  on  the  water-bath,  extract  the  residue  with  strong  alcohol, 
decolorize  when  necessary  with  animal  charcoal,  and  filter  while 
warm.  The  urea  which  crystallizes  on  cooling  is  purified  by 
recrystallization  from  warm  alcohol.  A  further  quantity  of  urea 
may  be  obtained  from  the  mother-liquor  by  concentration.  The 
urea  is  purified  from  contaminating  mineral  bodies  by  redissolving  in 
alcohol-ether.  If  it  is  only  necessary  to  detect  the  presence  of  urea 
in  urine,  it  is  sufficient  to  concentrate  a  little  of  the  urine  on  a 
watch-glass  and  after  cooling  treat  with  an  excess  of  nitric  acid. 
In  this  way  we  obtain  crystals  of  urea  nitrate. 

Quantitative  Estimation  of  Urea  in  urine.  The  methods 
suggested  for  this  purpose  are  those  of  Liebig,  by  titration,  of 
Heintz  and  Ragsky,  also  that  of  Kjeldahl,  by  which  the  total 
nitrogen  is  determined,  and  those  of  Bunsen  and  Knop-Hufner, 
where  urea  is  intended  to  be  determined  as  such.  Among  these 
methods,  that  of  Liebig,  which  is  perhaps  the  one  most  frequently 
employed  by  physicians,  will  here  be  carefully  explained.  In  regard 
to  the  others,  whose  chief  points  only  will  be  spoken  of  here,  the 
student  is  referred  to  other  text-books. 

Liebig's  method  is  based  upon  the  fact  that  a  dilute  solution 
of  mercuric  nitrate  under  proper  conditions  precipitates  all  the  urea 
forming  a  compound  of  constant  composition.  As  indicator,  a 
soda  solution  or  a  thin  paste  of  sodium  bicarbonate  is  used.  An 
excess  of  mercuric  nitrate  produces  herewith  a  yellow  or  yellowish- 
brown  combination,  while  the  combination  of  urea  and  mercury  is 
white.  Pfluger  has  given  full  particulars  of  this  method;  there- 
fore we  will  describe  Pfluger's  modification  of  Liebig's  method. 

As  phosphoric  acid  is  also  precipitated  by  the  mercuric- 
nitrate  solution,  this  must  be  removed  from  the  urine  by  the  addi- 


342  PHTSIOLOQICAL  CHEMISTRY. 

tion  of  a  baryta  solution  before  titration.  Pfluger  also  suggested 
that  the  acidity  produced  by  the  mercury  solution  be  neutralized 
with  a  soda  solution.  The  liquids  necessary  for  the  titration  are 
the  following : 

1.  Mercuric  Nitrate  Solution.  This  solution  is  calculated  for  a  2^ 
urea  solution,  and  20  c.  c.  of  the  first  should  correspond  to  10  c.  c.  of 
the  latter.  Each  c.  c.  of  the  mercury  solution  corresponds  to 
0.01  grm.  urea.  As  a  small  excess  of  HgO  is  necessary  in  the 
urine  to  make  the  final  reaction  (with  alkali  carbonate  or  bicarbon- 
ate) appear,  each  c.  c.  of  the  mercury  solution  must  contain  0.0772 
instead  of  0.0720  grm.  HgO.  The  mercury  solution  contains  there- 
fore 77.2  grms.  HgO  in  one  litre. 

The  solution  may  be  prepared  from  pure  mercury  or  mercuric  oxide  by 
dissolving  in  nitric  acid.  The  solution,  freed  as  completely  as  possible  from  an 
excess  of  acid,  is  diluted  by  the  careful  addition  of  water,  stirring  meanwhile, 
until  it  has  a  specific  gravity  of  1.10  or  a  little  higher  at  -j-  20°  C.  The  solu- 
tion is  standardized  with  a  2^  solution  of  pure  urea  which  has  been  dried 
over  sulphuric  acid,  and  the  operation  conducted  as  will  be  described  later. 
If  the  solution  is  too  concentrated,  it  is  corrected  by  the  careful  addition  of  the 
necessary  amount  of  water,  avoiding  basic  salt,  and  titrated  again.  The  solu- 
tion is  correct  if  19.8  c.  c.  of  it  is  added  at  once  to  10  c.  c.  of  the  urea  solu- 
tion and  the  necessary  quantity  of  normal  soda  solution  (11-12  c.  c.  or  more)  to 
completely  neutralize  the  liquid,  gives  the  final  reaction  when  20  c.  c.  of  the 
mercury  solution  have  been  employed. 

2.  Baryta  Solution.  This  consists  of  1  vol.  barium-nitrate  and 
2  vols,  barium-hydrate  solution,  both  saturated  at  the  ordinary 
temperature. 

3.  Wormal  Soda  Sohttion.  This  solution  contains  53  grms.  pure 
anhydrous  carbonate  in  1  litre  of  water.  According  to  Ppluger,  a 
solution  having  a  specific  gravity  of  1.053  is  sufficient.  The 
amount  of  this  soda  solution  necessary  to  completely  neutralize  the 
acid  set  free  during  the  titration  is  determined  by  titrating  with  m. 
pure  2^  urea  solution.  .To  facilitate  operations  a  table  can  be 
made  showing  the  quantity  of  soda  solution  necessary  when  from 
10  to  35  c.  c.  of  the  mercury  solution  is  used. 

Before  the  titration  the  following  must  be  considered.  The 
chlorides  of  the  urine  interfere  with  the  titration  in  that  a  part  of 
the  mercuric  nitrate  is  transformed  into  mercuric  chloride,  which 
does  not  precipitate  the  urea.  The  chlorides  of  the  urine  are  there- 
fore removed  by  a  silver-nitrate  solution,  which  also  removes  any 
bromine  or  iodine  combinations  which  may  exist  in  the  urine.  If 
the  urine  contains  albumin  in  noticeable  amounts,  it  must  be 
removed  by  coagulation  and  the  addition  of  acetic  acid,  but  care 
must  be  taken  that  the  concentration  and  the  volume  of  the  urine 
is  not  changed  during  these  operations.  If  the  urine  contains 
ammonium   carbonate  in  notable  quantities,  caused  by  alkaline 


TEE  UBINE.  343 

fermentation,  this  titration  method  cannot  be  applied.  The  same 
is  true  of  urine  containing  leucin,  tyrosin  or  medicinal  preparations, 
precipitated  by  mercuric  nitrate. 

In  cases  where  the  urine  is  free  from  albumin  or  sugar  and  not 
specially  poor  in  chlorides,  the  quantity  of  urea,  and  also  the 
approximate  quantity  of  mercuric  nitrate  necessary  for  the  titration, 
may  be  learned  from  the  specific  gravity.  A  specific  gravity  of 
1.010  corresponds  to  about  10  p.  m.,  the  specific  gravity  1.015 
generally  somewhat  less  than  15  p.  m.,  and  the  specific  gravity 
1.015-1.020  about  15-20  p.  m.  urea.  With  a  specific  gravity  higher 
than  1.020  the  urine  generally  contains  more  than  20  p.  m.  of  urea, 
and  above  this  point  the  amount  of  urea  increases  much  more 
rapidly  than  the  specific  gravity,  so  that  at  a  specific  gravity  of 
1.030  it  contains  over  40  p.  m.  urea.  In  fevers,  urine  with  a 
specific  gravity  above  1.020  sometimes  contains  30-40  p.  m,  urea, 
or  even  more. 

Preparation  for  the  Titration.  If  a  large  amount  of  urea 
is  suspected  from  a  high  specific  gravity,  the  urine  must  first  be 
diluted  with  a  carefully-measured  quantity  of  water,  so  that  the 
amount  of  urea  is  reduced  below  30  p.  m.  In  a  special  portion  of 
the  same  urine  the  amount  of  chlorides  is  determined  by  one  of  the 
methods  which  will  be  given  later,  and  the  number  of  c.  c.  of  silver- 
nitrate  solution  necessary  is  noted.  Then  a  larger  quantity  of  urine, 
say  100  c.  c,  is  mixed  with  one  half  or,  if  this  is  not  suflficient  to 
precipitate  all  the  sulphuric  and  phosphoric  acids,  with  an  equal  vol- 
ume of  the  baryta  solution,  it  is  then  allowed  to  stand  a  little  while, 
and  the  precipitate  is  filtered  through  a  dried  filter.  From  the  fil- 
trate containing  the  urine  diluted  with  water  a  proper  quantity, 
corresponding  to  about  60  c.  c.  of  the  original  urine,  is  measured, 
and  exactly  neutralized  with  nitric  acid  added  from  a  burette,  so 
that  the  exact  quantity  employed  is  known.  The  neutralized  mix- 
ture of  urine  and  baryta  is  treated  with  the  proper  quantity  of 
silver-nitrate  solution  necessary  to  completely  precipitate  the  chlo- 
rides, which  was  ascertained  by  a  previous  determination.  The  mix- 
ture containing  a  known  volume  of  urine  is  now  filtered  through  a 
dried  filter  into  a  flask,  and  from  the  filtrate  an  amount  is  measured 
corresponding  to  10  c.  c.  of  the  original  urine. 

Execution  of  the  Titration.  Nearly  the  total  quantity  of 
mercuric-nitrate  solution  to  be  used,  and  which  is  known  from  the 
specific  gravity  of  the  urine,  is  added  at  once,  and  immediately 
afterwards  the  quantity  of  soda  solution  necessary,  as  indicated  by 
the  table.  If  the  mixture  becomes  yellowish  in  color,  then  too  much 
mercury  solution  has  been  added  and  another  determination  must 
be  made.  If  the  test  remains  white,  and  if  a  drop  taken  out  and 
placed  on  a  glass  plate  with  a  dark  background  and  stirred  with  a 
drop  of  a  thin  paste  of  sodium  bicarbonate  does  not  give  a  yellow 


344  PHYSIOLOGICAL  GHEMISTBT. 

color,  the  addition  of  mercury  solution  is  continued  by  adding  ^ 
and  then  ^-^  c.  c,  and  testing  after  each  addition  in  the  following 
way :  A  drop  of  the  mixture  is  placed  on  a  glass  plate  with  a  dark 
background  beside  a  small  drop  of  the  bicarbonate  paste.  If  the 
color  after  stirring  the  two  drops  together  is  still  white  after  a  few' 
seconds,  then  more  mercury  solution  must  be  added;  if,  on  the  con- 
trary, it  is  yellowish,  then — if  not  too  much  mercury  solution  has 
been  added  by  inattention — the  result  to  yV  c.  c.  has  been  found. 
By  this  approximate  determination,  which  is  sufficient  in  many 
cases,  we  have  learned  the  minimum  amount  of  mercury  solution 
necessary  to  add  to  the  quantity  of  urine  in  question,  and  we  now 
proceed  to  the  final  determination. 

A  second  quantity  of  the  filtrate,  corresponding  to  10  c.  c.  of 
the  original  urine,  is  filtered,  and  the  same  quantity  of  mercury 
solution  added  at  one  time  as  was  found  necessary  to  produce  the 
final  reaction,  and  immediately  after  the  corresponding  amount  of 
soda  solution,  which  must  not  indicate  the  end  of  the  reaction.  Then 
add  the  mercury  solution  in  -^-^  c.  c.  without  neutralizing  with  soda, 
until  a  drop  taken  out  and  mixed  with  the  soda  solution  gives  a  yellow 
coloration.  If  this  final  reaction  is  obtained  after  the  addition  of 
0.1-0.3  c.  c,  then  the  titration  may  be  considered  as  finished.  If, 
on  the  contrary,  a  larger  quantity  is  necessary,  the  addition  of  the 
mercury  solution  must  be  continued  until  a  final  reaction  is  ob- 
tained with  simple  carbonate,  and  the  titration  repeated  again,  add- 
ing the  quantity  of  mercury  solution  used  in  the  previous  test  at 
one  time,  and  also  adding  the  corresponding  amount  of  soda  solu- 
tion. If  we  obtain  the  end  reaction  by  .the  addition  of  ^^  c.  c,  we 
may  consider  the  titration  as  finished. 

If  in  each  titration  a  quantity  of  filtrate  containing  urine  and 
baryta  corresponding  to  10  c.  c.  of  the  primitive  urine  is  used,  then 
the  calculations  are  very  simple,  since  1  c.  c.  of  mercuric-nitrate 
solution  corresponds  to  0.01  grm.  of  urea.  As  the  mercury  solu- 
tion is  made  for  a  2^  urea  solution,  the  filtrate  of  urine  and  baryta 
being  generally  deficient  in  urea  (if  the  quantity  of  urea  is  above 
2^,  it  is  easy  to  avoid  any  mistake  by  diluting  the  urine  at  the 
beginning  of  the  operation),  a  mistake  occurs  here  which  can  be  cor- 
rected in  the  following  way,  according  to  Pflijger:  To  the  measured 
volume  of  the  filtrate  from  the  urine  (the  filtrate  with  baryta  after 
neutralization  with  nitric  acid,  precipitation  with  silver  nitrate  and 
filtration)  the  quantity  of  normal  soda  solution  employed  is  added, 
and  from  this  sum  the  volume  of  mercury  solution  used  is  sub- 
tracted. The  remainder  is  then  multiplied  by  0.08,  and  the  prod- 
uct subtracted  from  the  number  of  c.  c.  of  mercury  solution  used. 
Por  example,  if  the  filtrate  (urine  and  baryta  +  nitric  acid  +  silver 
nitrate)  measured  25.8  c.  c,  and  the  number  of  c.  c.  of  soda  solu- 
tion used  in  the  titration,  13.8  c.  c,  and  the  mercury  solution,  20.5 


THE   UEINE.  345 

c.  c,  we  have  then  20.5  —  |(39.6  —  20.5)  X  0.08}  =  20.5  —  1.53  = 
18.97,  and  the  corrected  quantity  of  mercury  solution  is  therefore 
18.97  c.  c.  If  the  measured  c.  c.  of  the  filtrate  (in  this  case  25.8  c.  c.) 
corresponds  to  10  c.  c.  of  the  original  urine,  then  the  amount  of 
urea  is  18.97  X  0.01  =  0.1897  =  18.97  p.  m.  urea. 

Besides  the  urea  other  nitrogenized  constituents  of  the  urine 
are  precipitated  by  the  mercury  solution.  By  the  titration  we 
really  do  not  obtain  the  quantity  of  urea,  but,  as  Pfluger  haa 
shown,  the  total  quantity  of  nitrogen  in  the  urine  expressed  as 
urea.  As  the  urea  contains  46.67  p.  c.  N,  the  total  quantity  of 
nitrogen  in  the  urine  may  be  calculated  from  the  quantity  of  urea 
found. 

The  results  obtained  by  Liebig-Pfluger's  titration  method 
for  the  total  nitrogen,  Pfluger  has  shown,  correspond  well  with 
the  results  obtained  by  Kjeldahl's  method,  which  was  first  (1861) 
used  by  Almen  for  urea  determinations,  and  modified  by  PFLiJGER 
and  BoHLAXD.  This  method  consists  in  heating  the  urine  a  cer- 
tain time  with  an  excess  of  concentrated  or  fuming  sulj)huric  acid 
(5  c.  c.  urine  and  40  c.  c.  sulphuric  acid)  until  all  the  nitrogen  has 
been  converted  into  ammonia,  and  after  the  addition  of  an  excess 

of  caustic  soda  the  ammonia  is  distilled  into  —  sulphuric  acid  and 

the  amount  of  ammonia  distilled  over  is  determined  by  titration. 

Buxsen's  Urea  Determination.  The  principle  of  this 
method  consists  in  heating  the  urine  or  urea  solution  in  a  sealed 
glass  tube  to  a  high  temperature  with  an  alkaline  barium-chloride 
solution.  The  urea  splits  into  carbon  dioxide  and  ammonia,  which 
may  be  determined  separately.  This  method  has  been  very  care- 
fully tested  by  PrLiJGER  and  his  pupils  Bohland  and  Bleibtreu, 
and  essentially  improved.  They  found  that  very  accurate  results 
can  be  obtained  by  this  method  if  the  other  nitrogenized  constit- 
uents of  the  urine  are  first  precipitated  by  a  mixture  of  hydro- 
chloric acid  and  phospho-tungstic  acid,  and  then  the  filtrate  made 
faintly  alkaline  with  milk  of  lime,  and  lastly  heated  with  alkaline 
barium-chloride  solution  in  a  sealed  tube.  The  carbon  dioxide 
and  the  ammonia  can  be  determined  (by  distilling  with  magnesia 

and  receiving  the  distillate  in  —  acid  and  titrating).     In  the  last 


346  PHYSIOLOOICAL   CHEMISTRY. 

case  a  correction  must  be  made  (according  to  Schlosing's 
method)  for  the  ammonia  pre-existing  in  the  urine.  Pfluger 
and  Bleibtreu  have  essentially  changed  tliis  method  in  the  fol- 
lowing way :  They  precipitate  the  other  nitrogenized  urinary  con- 
stituents with  hydrochloric  acid  and  phospho-tungstic  acid,  make  the 
filtrate  faintly  alkaline  with  milk  of  lime,  determine  the  pre-existing 
ammonia  in  a  part  of  this  filtrate  according  to  Schlosing's 
method  (observing  certain  precautions),  and  then  placing  the  other 
part  of  the  filtrate  (about  15  c.  c.)  in  a  large  flask  which  contains 
10  grms.  crystallized  phosphoric  acid,  heat  to  330°-260°  C.  for 
about  three  hours.  All  the  urea  is  decomposed,  and  the  ammonia 
split  oif  combines  with  the  phosphoric  acid.  After  cooling,  an 
excess  of  caustic  soda  is  added  and  the  ammonia  distilled  into  a 
titrated  acid,  which  must  then  be  retitrated.  After  subtracting  the 
quantity  of  pre-existing  ammonia  very  accurate  results  are  obtained 
for  the  ammonia  originating  from  the  urea  (and  perhaps  from  an 
unknown  ureid  present  in  the  urine). 

KNOP-HtJFN"ER's  METHOD  is  based  on  the  fact  that  urea  by  the 
action  of  sodium  hypobromite  splits  into  water,  carbon  dioxide 
(which  dissolves  in  the  alkali),  and  nitrogen,  whose  volume  is 
measured  (see  page  340).  This  method  is  less  accurate  than  the 
preceding  ones,  and  therefore  in  scientific  work  it  is  discarded.  It 
is  of  value  to  the  physician  and  for  practical  purposes  because  of 
the  ease  and  rapidity  with  which  it  may  be  performed,  even  though 
it  may  not  give  very  accurate  results.  For  practical  purposes  a 
series  of  different  apparatus  have  been  constructed  to  facilitate 
the  use  of  this  method.  Among  these  the  ureometer  of  Esbach 
deserves  to  be  especially  mentioned.'     In  regard  to  the  reagents 

'  Dr.  Chas.  a.  Doremus  has  constructed  a  ureometer  of  the  very  simplest 
kind.  It  consists  of  two  parts.  First,  a  vertical  glass  tube  closed  at  the  top 
and  bent  sharply  below,  where  it  expands  into  a  bulb  having  an  orifice  at  its 
uppei-  part.  Secondly,  a  pipette  with  an  elastic  rubber  nipple.  Both  parts 
are  graduated  ;  the  vertical  tube  so  as  to  show  the  quantity  of  urea  (as  indi- 
cated by  the  volume  of  nitrogen)  in  each  cubic  centimetre  of  urine  tested, 
while  the  pipette  is  graduated  so  as  to  show  one  cubic  centimetre.  The 
instrument  is  used  thus:  First  the  vertical  tube  is  filled  with  the  alkaline 
sodium-hypobromite  solution  in  the  following  manner  :  holding  it  vertically, 
the  operator  pours  the  solution  into  the  bulb,  and  when  it  is  rather  more  than 
half  full  he  inclines  the  apparatus  horizontally  until  the  entire  tube  is  filled 
and  a  little  left  in  the  bulb— say  one  third  or  thereabouts.  Then  he  restores 
it  to  the  vertical  position.     He  now  draws  into  the  pipette,  by  means  of  the 


<  TEE  URINE.  347 


c^ 


necessary  for  the  determination  of  urea,  and  also  for  instructions  in 
the  use  of  this  instrument,  we  must  refer  the  reader  to  the  direc- 
tions accompanying  the  apparatus.  For  pure  urea  solutions  Es- 
bach's  apparatus  gives  quite  exact  results.  The  determination  of 
urea  in  urine  by  this  method  always  gives  results  somewhat  too 
low,  and  as  a  rule  a  result  is  obtained  which  on  an  average  is  about 
0.1^  lower  than  that  obtained  with  Liebig's  titration  method. 

Creatinin,  C.H^NaO,  or  NH  :  C<^^^^?^  ,  is  generally  con- 
sidered as  the  anhydride  of  creatin  (see  page  257)  found  in  the 
muscles.  It  occurs  in  human  urine  and  in  that  of  certain  mam- 
malia. It  has  also  been  found  in  ox-blood  (Voit),  milk,  though  in 
very  small  amounts  (Weyl),  and  in  the  flesh  of  certain  fishes. 

The  quantity  of  creatinin  in  human  urine  is  for  a  grown  man, 
voiding  a  normal  quantity  of  urine  in  the  24  hours,  0.6-1.3  grms. 
(Neubauer),  or  on  an  average  1  grm.  The  quantity  is  dependent 
on  the  food,  and  decreases  in  starvation.  Sucklings  do  not  gener- 
ally eliminate  any  creatinin,  and  it  only  appears  in  the  urine  when 
tne  milk  is  replaced  by  other  food.  The  quantity  of  creatinin  in 
urine  varies  as  a  rule  with  the  quantity  of  urea,  although  it  is  in- 
creased more  by  flesh  (because  the  flesh  contains  creatin)  than  by 
albumin.  Grocco  claims  that  the  elimination  of  creatinin  is  in- 
creased by  muscular  activity,  which  is  contrary  to  the  statements 
of  HoFMANN"  and  others.  The  behavior  of  creatinin  in  disease  is 
little  known.  By  increased  exchange  of  material  the  amount  is 
increased,  while  by  decreased  exchange  of  material,  as  in  anaemia 
and  cachexia,  it  is  diminished. 

Creatinin  crystallizes  in  colorless,  shining  monoclinic  prisms 
which  diifer  from  creatin  crystals  in  not  becoming  white  with  loss 
of  water  when  heated  to  100°  C.  It  dissolves  in  11.5  parts  cold 
water,  but  more  easily  in  warm  water.     It  requires  nearly  100  parts 


rubber  nipple,  a  cubic  centimetre  of  the  urine  to  be  tested,  which  should  be 
taken  from  the  total  excretion  of  the  twenty-four  hours,  the  exact  quantity  of 
which  should  be  noted.  The  end  of  the  pipette  is  passed  into  the  bulb  until  the 
point  is  exactly  under  the  vertical  tube,  and  slowly  compress  the  nipple.  The 
urine  being  lighter  than  the  hypobromite  solution  "rises  through  it,  and  on  its 
way  the  contained  urea  is  decomposed  and  its  nilrogen  .set  free.  The  quantity 
of  urea  contained  in  the  one  cubic  centimetre  of  urfne  used  is  read  off  on  the 
instrument. — Translator. 


348  PET8I0L0OICAL  CHEM18TRT. 

cold  absolute  alcohol  for  solution,  but  it  is  more  soluble  in  warm 
alcohol.  It  is  nearly  insoluble  in  ether.  In  alkaline  solution  crea- 
tinin  is  converted  into  creatin  very  easily  on  warming. 

Creatinin  gives  an  easily-soluble  crystalline  combination  with 
hydrochloric  acid.  A  solution  of  creatinin  acidified  with  mineral 
acids  gives  crystalline  precipitates  with  phospho-tungstic  or  phos- 
pho-molybdic  acids,  even  in  very  dilute  solutions  (1  :  10,000)  (Ker- 
jSTEr).  It  is  precipitated,  like  urea,  with  mercuric-nitrate  solution. 
Among  the  compounds  of  creatinin,  that  with  zinc  chloride,  crea- 
tinin zinc  chloride  (C4H7N30)2ZnCl2 ,  is  of  special  interest.  This 
combination  is  obtained  when  a  sufficiently  concentrated  solution 
of  creatinin  in  alcohol  is  treated  with  a  concentrated,  faintly-acid 
solution  of  zinc  chloride.  Free  mineral  acids  dissolve  the  combina- 
tion, but  this,  however,  is  prevented,  when  they  are  present,  by  an 
addition  of  sodium  acetate.  In  the  impure  state,  as  ordinarily  ob- 
tained from  urine,  creatinin  zinc  chloride  forms  a  sandy,  yellowish 
powder  which  under  the  microscope  appears  as  fine  needles  form- 
ing concentric  groups,  mostly  complete  rosettes  or  yellow  balls  or 
tufts,  or  grouped  as  brushes.  On  slowly  crystallizing,  or  when 
very  pure,  more  sharply-defined  prismatic  crystals  are  obtained. 
This  combination  is  sparingly  soluble  in  water. 

Creatinin  acts  as  a  reducing  agent.  Mercuric  oxide  is  reduced 
to  metallic  mercury,  and  oxalic  acid  and  methylguanidin  (methyl- 
uramin)  are  formed.-  Creatinin  also  reduces  copper  hydroxide  in 
alkaline  solution,  forming  a  colorless  soluble  combination,  and  only 
after  continuous  boiling  with  an  excess  of  copper  salts  is  free  sub- 
oxide of  copper  formed.  Creatinin  interferes  with  Trommer's  test 
for  sugar,  partly  because  it  has  a  reducing  action  and  partly  by 
retaining  the  copper  suboxide  in  solution.  The  combination  with 
copper  suboxide  is  not  soluble  in  a  saturated-soda  solution  and  if 
a  little  creatinin  is  dissolved  in  a  cold,  saturated-soda  solution  and 
then  a  few  drops  of  Feeling's  reagent  added,  a  white  flocculent 
combination  separates  after  heating  to  50°-60°  0.  and  then  cooling 
(y.  MaschSe's  reaction).  An  alkaline  bismuth  solution  (see  Sugar 
Tests)  is  not  reduced  by  creatinin. 

If  we  add  a  few  drops  of  a  freshly-prepared  very  dilute  sodium 
nitroprusside  (sp.  gr.  1.003)  to  a  dilute  creatinin  solution  (or  to 
the  urine)  and  then  a  few  drops  of  caustic  soda,  a  ruby-red  liquid 


THE  URINE.  349 

is  obtained  which  quickly  turns  yellow  again  (Weyl's  reaction). 
If  we  use  ammonia  instead  of  caustic  soda  in  this  reaction,  the  red 
color  is  not  obtained  (differing  from  aceton  and  ethyl-diacetic  acid, 
Le  Nobel).  If  the  above  solution,  which  has  become  yellow,  is 
treated  with  an  excess  of  acetic  acid  and  heated,  the  solution  be- 
comes first  green  and  then  blue  (Salkowski);  finally  a  precipitate 
of  Prussian  blue  is  obtained.  If  a  solution  of  creatiniu  in  water  (or 
urine)  is  treated  with  a  watery  solution  of  picric  acid  and  a  few 
drops  of  a  dilute  soda  solution,  a  red  coloration  lasting  several  hours 
occurs  immediately  at  the  ordinary  temperature,  and  which  turns 
yellow  on  the  addition  of  acid  (Jaffe's  reaction).  Acetone  gives 
a  more  reddish-yellow  color.  Grape-sugar  gives  with  this  reagent  a 
red  coloration  only  after  heating. 

In  preparing  creatinin  from  urine  the  creatinin  zinc  chloride  is 
first  prepared  according  to  Neubauer's  method,  and  this  method 
is  also  employed  for  the  quantitative  estimation  of  creatinin.  In 
making  a  quantitative  estimation  200-300  c.  c.  of  urine  freed  from 
albumin  (by  boiling  with  acid)  and  from  sugar  (by  fermentation 
with  yeast)  are  measured,  alkalized  with  milk  of  lime,  and  treated 
with  CaCl2  solution  until  all  the  phosphoric  acid  is  precipitated ;  it 
is  filtered  and  washed  with  water,  the  filtrate  and  the  wash-water 
united,  and  evaporated  to  a  syrup  after  acidifying  with  acetic  acid. 
This  syrup  is  mixed  while  hot  with  50  c.  c.  of  95^-97^  alcohol. 
This  mixture  is  transferred  to  a  beaker,  and  the  residue  in  the 
evaporatiug-dish  is  completely  and  carefully  removed  and  added. 
The  liquid  is  allowed  to  stand  covered  for  at  least  eight  hours  in 
the  cold.  Then  it  is  filtered  through  a  small  filter,  the  precipitate 
washed  with  alcohol,  the  filtrate  evaporated  if  necessary  until  the 
volume  is  50-60  c.  c,  then  allowed  to  cool  and  i;  c.  c.  of  an  acid- 
free  zinc-chloride  solution  of  au  sp.  gr.  of  1.20  is  added ;  it  is  stirred, 
and  the  covered  beaker  is  left  standing  in  a  cool  place  for  two  or 
three  days.  The  precipitate  is  collected  on  a  small  dried  and 
weighed  filter,  using  the  filtrate  to  wash  the  crystals  from  the 
beaker.  After  allowing  the  crystals  to  completely  drain  off,  they 
are  washed  with  a  little  alcohol  until  the  filtrate  gives  no  reaction 
for  chlorine,  and  dried  at  100°  C.  100  parts  creatinin  zinc  chloride 
contain  62.42  parts  creatinin.  As  tiie  precipitate  is  never  quite 
pure,  the  quantity  of  zinc  must  be  carefully  determined,  in  exact 
experiments,  by  evaporating  with  nitric  acid,  heating,  washing  the 
oxide  of  zinc  with  water  (to  remove  any  NaCl),  drying,  heatings 
and  weighing.  22.4  parts  zinc  oxide  correspond  to  100  parts  crea- 
tinin zinc  chloride. 


350  PHYSIOLOGICAL  CHEMISTRY, 

The  preparation  of  creatinin  zinc  chloride  on  a  large  scale  from 
urine  is  done  in  the  same  way.  The  creatinin  is  obtained  from 
the  creatinin  zinc  chloride  by  boiling  with  lead  hydroxide,  filtering, 
decolorizing  the  filtrate  with  animal  charcoal,  evaporating,  treating 
the  residue  with  strong  alcohol  (which  leaves  the  creatin  undis- 
solved), evaporating  to  crystallization,  redissolving  in  water,  and 
recrystallizing. 

XaQthocreatinin.  This  body,  which  has  been  spoken  of  in  a  previous  chap- 
ter on  the  muscles,  has  been  found  in  dog's  urine  after  the  injection  of  crea- 
tinin into  the  abdominal  cavity  (Monaki),  and  in  human  urine  after  several 
hours  of  continuous  marching.  The  correctness  of  these  observations  is 
disputed  by  Stadthagen. 

Uric  Acid,  Ur,  O5H4N4O3.     The  structural  formula  of  this  acid, 

yNH.O.NH\ 
according  to  Medicus,  is  00<'  O.JSTH/CO,  and    this    acid 

\NH.C0 
may  therefore  be  considered,  from  its  constitution  as  a  derivate  of 
acrylic  acid,  as  acrylic  acid  diureid. 

Uric  acid  has  been  synthetically  prepared  by  Hoebaczewski  in 
several  ways.  On  fusing  urea  and  glycocoll,  uric  acid  is  formed 
according  to  the  formula  SCONaH^  +  C2H5NO2  =  CsH.N.Og  + 
2H2O  +  3NH3 ,  and  in  this  reaction  hydantoin  and  biuret  are  formed 
as  intermediate  products.  On  melting  methylhydantoin  with  urea 
or  methylhydantoin  with  biuret  or  with  allophanic-acid  amyl-ester 
HoRBACZEWSEi  obtained  methyl-uric  acid.  He  also  obtained  uric 
acid  on  heating  trichlor-lactic  acid,  or  still  better  trichlor-lactic  acid- 
amid,  with  an  excess  of  urea.  If  we  eliminate  from  the  reaction 
the  numerous  by-products  (cyanuric  acid,  carbon  dioxide,  etc.), 
then  this  process  may  be  expressed  by  the  formula  C3CI3H4O2N"  + 
2CO]Sr8H,  =  C5H,N,03  +  H2O  +  NH.Cl  +  2HC1. 

On  strongly  heating  uric  acid  it  decomposes  with  the  formation 

of  UREA,  HYDROCYAlSriC  ACID,  CYANURIC  ACID,  and  AMMONIA.      On 

lieating  with  concentrated  hydrochloric  acid  in  sealed  tubes  to 
170°  C.  it  splits  into  glycocoll,  carbon  dioxide,  and  ammonia. 
By  the  action  of  oxidizing  agents  a  splitting  and  oxidation  takes 
place,  and  either  monoureid  or  diureid  is  produced.  By  oxidation 
with  lead  peroxide,  carbon  dioxide,  oxalic  acid,  urea,  and 
ALLANTOIN,  which  last  is  glyoxyldiureid,  are  produced  (see  below). 
By  oxidation  with  nitric  acid  in  the  cold  urea  and  a  monoureid,  the 


THE  URINE.  351 

mesoxalyl  urea  or  alloxan",  are  obtained,  CsH^NtOs  +  0  +  HgO  = 
CiHaNaOi  +  (NH2)2CO.  On  warming  with  nitric  acid,  uric  acid 
yields  alloxan,  carbon  dioxide,  and  oxalyl  urea  or  parabanic  acid, 
C3H2N2O3.  By  the  addition  of  water  the  parabanic  acid  passes  into 
oxALURic  ACID,  C3H4N2O1 ,  traces  of  which  are  found  in  the  urine 
and  which  easily  split  into  oxalic  acid  and  urea. 

Uiic  acid  occurs  most  abundantly  in  the  urine  of  birds  and  of 
scaly  amphibians,  in  which  animals  the  greater  part  of  the  nitrogen 
of  the  urine  appears  in  this  form.  Uric  acid  occurs  frequently  in 
the  urine  of  carnivorous  mammalia,  but  is  sometimes  absent;  in 
urine  of  herbivora  it  is  habitually  present,  though  only  as  traces;  in 
human  urine  it  occurs  in  greater  but  still  small  and  variable 
amounts.  Traces  of  uric  acid  are  also  found  in  several  organs  and 
tissues,  as  in  the  spleen,  lungs,  heart,  pancreas,  liver  (especially  in 
birds),  and  in  the  brain.  It  habitually  occurs  in  the  blood  of  birds 
(Meissner).  Traces  have  been  found  in  human  blood  under 
normal  conditions  (Abeles),  but  especially  in  gout  (Garrod). 
Uric  acid  also  occurs  in  large  quantities  in  "chalk-stones,"  certain 
urinary  calciili,  and  in  guano.  It  has  also  been  detected  in  the 
urine  of  insects  and  certain  snails. 

The  amount  of  uric  acid  eliminated  with  the  human  urine  is 
subject  to  considerable  variation,  but  amounts  on  an  average  to 
0.7  grm.  during  24  hoiirs  on  a  mixed  diet.  On  a  vegetable  diet 
the  amount  is  smaller,  and  on  an  abundant  meat  diet  it  may  rise  to 
2  grms.  and  over.  The  relationship  of  the  uric  acid  to  the  urea  on 
a  mixed  diet  is  on  an  average  1 :  50-1 :  70.  In  new-born  infants  and 
in  the  first  days  of  life  the  elimination  of  uric  acid  is  increased 
(Mares),  and  the  relation  between  the  uric  acid  and  urea  is  about 
1 :  13-1-4.  After  taking  glycerin  the  amount  of  uric  acid  is  in- 
creased (HoRBACZEWSKi  and  Kanera),  while  it  is  not  increased  by 
sodium  acrylate  (Horbaczewski). 

Uric  acid  when  introduced  into  the  organism  of  a  dog  is  in  great 
part  converted  into  urea,  and  as  urea  is  also  formed  by  the  action 
of  oxidizing  agents  on  uric  acid  outside  of  the  body,  uric  acid  has 
been  often  considered  as  a  step  towards  the  formation  of  urea  in 
the  organism.  Such  a  view  is  not,  however,  well  founded,  and  the 
statement  that  an  incomplete  supply  of  oxygen  and  diminished 
oxidation  cause  an  increased  formation  of  uric  acid  has  not  been 


352  PHYSIOLOGICAL   CHEMISTRY. 

proved.  With  regard  to  the  pathological  relations  we  really  only 
know  two  conditions  in  which  the  elimination  of  uric  acid  is 
increased,  namely,  in  fever  and  leucaemia.  In  fevers  the  elimina- 
tion of  uric  acid  is  increased  because  of  an  increased  waste  of  the 
organism.  In  leucaemia  the  elimination  is  increased  absolutely  as 
well  as  relatively  to  the  urea  (Eanke,  Salkowski,  Fleischer  and 
Pekzoldt,  Stadthagbn,  and  others),  and  the  relationship  of  the 
elimination  of  uric  acid  to  the  urea  may  be  1:16-1:12.  The 
elimination  of  uric  acid  may  be  diminished  in  gout  shortly  before 
and  during  the  attack,  because  the  uric  acid  is  retained  in  the 
body.  A  decrease  in  the  elimination  of  uric  acid  is  observed  also  in 
a  diminished  exchange  of  material,  also  after  the  use  of  quinine, 
caffeine,  and  certain  other  medicines. 

J^ormation  of  Uric  Acid  in  the  organism.  The  formation  of  uric 
acid  in  birds  is  increased  by  the  administration  of  ammonia-salts 
(v.  Schroder).  Urea  acts  in  the  same  way  (Meyer  and  Jaffe), 
while  in  the  organism  of  mammalia  uric  acid  is  more  or  less  com- 
pletely converted  into  urea.  Minkowski  observed  in  geese  with 
their  livers  extirpated  a  very  significant  decrease  in  the  elimination 
of  uric  acid,  while  the  elimination  of  ammonia  is  increased  to  a 
corresponding  degree.  This  indicates  a  participation  of  ammonia 
in  the  formation  of  uric  acid  in  the  organism  of  birds  ;  and  as 
Minkowski  has  also  found  after  the  extirpation  of  the  liver  that 
considerable  amounts  of  lactic  acid  occur  in  the  urine,  it  is  prob- 
able that  the  uric  acid  in  birds  is  produced  in  the  liver,  perhaps 
from  lactic  acid  and  ammonia  by  synthesis.  Amido-acids — leucin, 
glycocoll,  and  aspartic  acid — increase  the  elimination  of  uric  acid  in 
birds  (v.  Knieriem),  but  whether  the  amido-acids  are  first  decom- 
posed with  the  splitting  off  of  ammonia  is  still  unknown,  v.  Mach 
has  shown  that  a  small  part  of  the  uric  acid  in  birds  originates  from 
hypoxanthin,  and  a  similar  origin  for  the  uric  acid  of  mammalia  is 
also  very  probable  (Minkowski). 

After  the  extirpation  of  the  kidneys  of  snakes  and  birds 
y.  Schroder  has  observed  an  accumulation  of  uric  acid  in  the  blood 
and  tissues.  This  shows  that  the  kidneys  of  these  animals  are  not 
the  only  source  of  uric  acid,  and  any  direct  proof  of  the  formation 
of  this  acid  in  the  kidneys  has  not  to  the  present  time  been  demon- 
strated.   A  direct  relationship  between  the  spleen  and  the  forma- 


THE   URINE.  353 

tion  of  uric  acid,  also  in  man,  has  been  sought  by  many  investigators 
(Ranke,  Kuhne),  and  in  support  of  this  view  they  claim  that  the 
elimination  of  uric  acid  is  increased  in  diseases  in  which  the  spleen 
is  enlarged,  also  that  the  elimination  of  uric  acid  by  the  urine  is 
decreased  when  the  volume  of  the  spleen  is  diminished  by  the 
administration  of  large  quantities  of  quinine.  That  uric  acid  is 
formed  in  the  spleen  receives  additional  proof  from  the  investiga- 
tions of  HoRBACZEWSKi.  He  found  a  considerable  new  formation 
of  uric  acid  when  he  allowed  the  pulp  of  the  spleen  and  blood  of 
calves  to  act  upon  each  other  at  the  ordinary  temperature,  at  the 
same  time  passing  a  stream  of  air  through  the  mass.  He  also 
obtained  extracts  from  the  pulp  of  the  spleen  with  boiling  water, 
which  yielded  uric  acid  after  the  action  of  the  blood.  This  produc- 
tion must  depend  chiefly  upon  decomposition  products  of  nuclein 
(xanthin  bodies).  Horbaczewski  claims  that  probably  the 
lymphatic  elements  are  here  concerned,  a  statement  which  coincides 
with  the  increased  elimination  of  uric  acid  in  lineal  leuceemia,  also 
with  the  parallelism  existing  between  the  digestion-leucocytes  and 
the  increased  elimination  of  uric  acid  occurring  after  taking  food. 
We  have  no  positive  basis  for  the  statement  that  uric  acid  is  formed 
in  the  liver  of  man  and  mammalia,  but  the  formation  of  uric  acid 
in  the  liver  of  birds  is  shown  to  be  highly  probable  by  the  researches 
of  Minkowski. 

Properties  and  Reactions  of  Uric  Acid.  Pure  uric  acid  is  a  white, 
odorless,  and  tasteless  powder  consisting  of  very  small  rhombical 
prisms  or  plates.  Impure  uric  acid  is  easily  obtained  as  somewhat 
larger,  colored  crystals. 

In  quick  crystallization,  small,  apparently  colorless,  thin,  four- 
sided  rhombic  prisms,  which  can  only  be  seen  by  the  aid  of  the 
microscope,  are  formed,  and  these  sometimes  appear  as  spools 
because  of  the  rounding  of  their  obtuse  angles.  The  plates  are 
sometimes  six-sided,  irregularly  developed ;  in  other  cases  they  are 
rectangular  with  partly  straight  and  partly  jagged  sides;  and  in 
other  cases  they  show  still  more  irregular  forms,  the  so-called  dumb- 
bells, etc.  In  slow  crystallization,  as  when  the  urine  deposits  a 
sediment  or  when  treated  with  acid,  large,  always  colored  crystals 
separate.  Examined  with  the  microscope  these  crystals  appear 
always  yellow  or  yellowish  brown   in  color.     The  most  ordinary 


354  PHY8I0L0OICAL  CHEMISTBT. 

form  is  the  whetstone  shape  formed  by  the  rounding  off  of  the 
obtuse  angles  of  the  rhombic  plate.  The  whetstones  are  numerous, 
connected  together,  two  or  more  crossing  each  other.  Besides  these 
forms,  rosettes  of  prismatic  crystals,  irregular  crosses,  brown-colored 
rough  masses  of  crystals  which  assume  the  shape  of  needles  and 
prisms  occur,  also  other  different  forms. 

Uric  acid  is  insoluble  in  alcohol  and  ether;  it  is  rather  easily 
dissolved  in  boiling  glycerin,  very  difficultly  soluble  in  cold  water 
(14,000-15,000  parts);  and  difficultly  soluble  in  boiling  water  (in 
1800-1900  parts),  it  is  soluble  in  a  warm  solution  of  sodium 
diphosphate,  and  in  the  presence  of  an  excess  of  uric  acid  mono- 
phosphate and  acid  urate  are  produced.  Sodium  phosphate  is 
considered  as  a  solvent  for  the  uric  acid  in  the  urine.  Uric  acid  is 
dissolved  without  decomposing  in  concentrated  sulphuric  acid.  It 
is  completely  precipitated  from  the  urine  by  picric  acid  (Jaffe). 

Uric  acid  forms  with  bases  two  series  of  salts,  neutral  and  acid. 
Of  the  alkali  urates  the  neutral  potassium  and  lithium  salts  dis- 
solve the  most  easily,  and  the  ammonium  salt  dissolves  with  the 
most  difficulty.  The  acid-alkali  urates  are  very  insoluble  and 
separate  as  a  sediment  {sedimentum-  lateritium)  from  concentrated 
urine  on  cooling.     The  salts  with  alkaline  earths  are  very  insoluble. 

If  a  little  uric  acid  in  substance  is  treated  with  a  few  drops  of 
nitric  acid,  the  uric  acid  dissolves  on  warming  with  a  strong 
development  of  gas,  and  after  thoroughly  drying  on  the  water-bath 
a  beautiful  red  residue  is  obtained,  which  turns  a  purple-red  (pur- 
purate  of  ammonium)  on  the  addition  of  a  little  ammonia.  If, 
instead  of  the  ammonia,  we  add  a  little  caustic  soda  (after  cooling), 
the  color  becomes  more  blue  or  bluish  violet.  This  color  disappears 
quickly  on  warming,  differing  from  certain  xanthin  bodies.  This 
reaction  is  called  the  murexide  test. 

Uric  acid  does  not  reduce  an  alkaline  solution  of  bismuth,  but 
does,  on  the  contrary,  an  alkaline  copper-hydroxide  solution.  In 
the  presence  of  only  a  little  copper  salt  we  obtain  a  white  precip- 
itate consisting  of  copper  urate.  In  the  presence  of  more  copper 
salt  red  suboxide  separates. 

If  a  drop  of  uric  acid  dissolved  in  sodium  carbonate  is  placed 
on  a  piece  of  filter-paper  which  has  been  previously  treated  with 
silver-nitrate  solution,  a  reduction  of  silver  oxide  occurs  producing 


THE  URINE.  355 

a  brownish-black  or,  in  the  presence  of  only  0.002  milligram  uric 
acid,  a  yellow  spot  (Schiff's  test). 

Preparation  of  Uric  Acid  from  Urine.  Filtered  normal  urine  is 
treated  with  20-30  c.  c.  of  25^  hydrochloric  acid  for  each  litre 
of  urine.  After  forty-eight  hours  collect  the  crystals  and  purify 
them  by  redissolving  in  dilute  alkali,  decolorizing  with  animal  char- 
coal and  reprecipitating  with  hydrochloric  acid.  Large  quantities  of 
uric  acid  are  easily  obtained  from  the  excrements  of  serpents  by 
boiling  them  with  dilute  caustic  potash  until  no  more  ammonia  is 
developed.  A  current  of  carbon  dioxide  is  passed  through  the 
filtrate  until  it  barely  has  an  alkaline  reaction;  dissolve  the 
separated  and  washed  acid  potassium  urate  in  caustic  potash,  and 
precipitate  the  uric  acid  by  addition  of  an  excess  of  hydrochloric 
acid  to  the  filtrate. 

Quantitative  Estimation  of  Uric  Acid  in  the  urine.  The  older 
method  of  Heintz,  somewhat  modified  by  Schwaneet,  is  in  its 
main  points  as  follows :  The  filtered  urine  free  from  albumin  and 
any  sediment  of  urates  (dissolved  by  warming)  is  concentrated 
when  too  dilute  to  a  sp.  gr.  of  1.020,  200  c.  c.  measured  off  and 
this  treated  with  10-20  c.  c.  hydrochloric  acid  of  a  sp.  gr.  of  1.12. 
After  allowing  this  mixture  to  stand  forty-eight  hours  in  a  cool 
place  the  precipitated  uric  acid  is  collected  on  a  small  weighed 
filter  (5-6  cm.  diameter),  and  the  crystals  which  have  adhered  to 
the  sides  of  the  glass  are  removed  by  means  of  a  glass  rod  tipped 
with  a  piece  of  rubber  tubing,  using  the  filtrate  to  wash  with. 
After  all  the  liquid  has  passed  through,  fill  the  filter  with  water 
and  allow  it  to  run  through  completely  before  adding  more  water; 
continue  until  the  wash-water  does  not  give  a  chlorine  reaction, 
then  dry  and  weigh.  A  part  of  the  uric  acid  always  remains  dis- 
solved in  the  filtrate.  The  filtrate,  including  the  wash-water,  must 
therefore  be  measured,  and  for  each  10  c.  c.  of  filtrate  (and  wash- 
water)  0.00048  grm.  uric  acid  must  be  added.  With  this  correc- 
tion this  determination  gives  the  same  results  as  the  following 
more  complicated  method. 

In  Salkowski  and  Ludwig's  method  the  uric  acid  is  precip- 
itated from  the  urine  by  silver-nitrate  solution,  treated  with 
magnesium  mixture,  and  the  uric  acid  removed  from  the  silver 
precipitate  and  weighed.  Uric-acid  determiiiations  according  to 
this  method  are  often  performed  according  to  the  treatment  sug- 
gested by  E.  LuDWiG,  which  requires  the  following  solutions : 

1.  An  AMMONiACAL  SILVER-NITRATE  solution  which  Contains  in  one  litre 
26  grms.  silver  nitrate  and  a  quantity  of  ammonia  sufficient  to  completely 
redissolve  the  precipitate  produced  by  the  first  addition  of  ammonia. 
2.  Magnesium  mixture.  Dissolve  100  grms.  crystallized  magnesium  chlo- 
ride in  water  and  add  enough  ammonia  so  that  the  liquid  smells  strongly  of  it, 


356  PHYSIOLOGICAL   CHEMISTRY. 

and  then  add  sufficient  ammonium  chloride  to  dissolve  the  precipitate  and 
lastly  dilute  to  1  litre.  3.  Sodium- sulphide  solution.  Dissolve  10  grms. 
caustic  soda  vphicb  is  free  from  nitric  and  nitrous  acids  in  1  litre  of  water. 
One  half  of  this  solution  is  completely  saturated  with  hydrogen  sulphide  and 
then  mixed  with  the  other  half. 

The  solutions  are  such  that  10  c.  c.  of  each  is  sufl&cient  for  100 
c.  c.  of  the  urine. 

100-300  c.  c,  according  to  concentration,  of  the  filtered  urine 
freed  from  albumin  (by  boiling  after  the  addition  of  a  few  drops  of 
acetic  acid)  are  poured  into  a  beaker.  In  another  vessel  mix  10-20 
c.  c.  of  the  silver  solution  with  10-30  c.  c.  of  the  magnesium  mix- 
ture, and  add  ammonia,  and  when  necessary  also  some  ammonium 
chloride,  until  the  mixture  is  clear.  This  solution  is  added  to  the 
urine  while  stirring,  and  the  mixture  allowed  to  stand  quietly  for 
I"  hour.  The  precipitate  is  collected  on  a  filter,  washed  with  am- 
moniacal  water,  and  then  returned  to  the  same  beaker  by  the  aid 
of  a  glass  rod  and  a  spirit-bottle  without  destroying  the  filter.  Now 
heat  to  boiling-point  10-20  c.  c.  of  the  alkaline  sulphide  solution, 
which  has  previously  been  diluted  with  an  equal  amount  of  water, 
and  allow  this  solution  to  flow  through  the  above  filter  into  the 
beaker  containing  the  silver  precipitate,  wash  with  boiling  water, 
and  warm  the  contents  of  the  beaker  on  the  water-bath  for  a  time, 
stirring  constantly.  After  cooling  filter  into  a  porcelain  dish,  wash 
with  boiling  water,  acidify  the  filtrate  with  hydrochloric  acid,  evap- 
orate to  about  15  c.  c,  add  a  few  drops  more  of  hydrochloric  acid, 
and  allow  it  to  stand  for  34  hours.  The  uric  acid  which  has  crys- 
tallized is  collected  on  a  small  weighed  filter,  washed  with  water, 
alcohol,  ether,  and  carbon  disulphide,  dried  at  100°-110°  C,  and 
weighed.  For  each  10  c.  c.  of  the  watery  filtrate  we  must  add 
0.00048  grm.  uric  acid  to  the  amount  found  directly.  Instead  of 
the  weighed  filter-paper  a  glass  tube  filled  with  glass  wool  may  be 
substituted.  This  tube  was  constructed  by  Ludwig,  and  is  de- 
scribed in  other  hand  books. 

Haycraft's  Method:  25  c.  c.  of  the  urine  are  first  treated 
with  1  grm.  bicarbonate,  then  made  strongly  alkaline  by  ammonia, 
and  lastly  precipitated  by  an  ammoniacal  silver  solution.  The 
carefully  washed  precipitate  is  dissolved  in  20-30^  nitric  acid  and 

this  solution  titrated  with  a  j^^  sulphocyanide  solution  according 

to  Volhard's  method.  Each  c.  c.  of  this  solution  corresponds  to 
0.00168  grm.  uric  acid.  This  method  has  been  modified  by  CzA- 
PEK.  After  the  addition  of  a  known  amount  of  silver  solution  of 
known  strength,  the  amount  of  silver  salts  remaining  in  the  urine 
after  all  the  uric  acid  has  been  precipitated  is  titrated  with  alkali 
sulphide.  The  advantage  of  Haycraft's  method  is  the  ease  and 
rapidity  with  which  it  can  be  performed,  and  it  is  therefore  recom- 


V 


THE   URINE.  357 

mended  for  clinical  purposes.  For  exact  determinations  it  is  not 
quite  reliable,  because  the  amount  of  silver  in  the  precipitate  of 
silver  urate  is  not  constant  (Salkowski).  Since  the  value  of  this 
method  has  been  the  subject  of  much  adverse  criticism,  we  will  not 
^ive  further  particulars. 

OxALURic  Acid,  C3H4N,04  =  (C0N,H3).C0.C00H.  This  acid,  whose 
relation  to  uric  acid  and  urea  has  been  spoken  of  above,  occurs  only  as  traces 
in  the  urine  as  ammonium  salts.  This  salt  is  not  directly  precipitated  by  CaCla 
and  NH3 ,  but  after  boiling,  when  it  is  decomposed  iuto  urea  and  oxalate.  In 
preparing  oxaluric  acid  from  urine  the  latter  is  filtered  through  animal  char- 
coal. The  oxalurate  retained  by  the  charcoal  may  be  obtained  by  boiling 
with  alcohol. 

COOH 
Oxalic  Acid,    CjHjOi,  or   nnQXTj  occurs  under  physiological 

conditions  in  very  small  amounts  in  the  urine,  about  0.03  grm.  in 
2-4  hours  (Fukbringer).  According  to  the  generally-received 
opinion  it  is  found  in  the  urine  as  calcium  oxalate,  which  is  kept 
in  solution  by  the  acid  phosphates  present.  Calcium  oxalate  is  a 
frequent  constituent  of  the  urinary  sediments,  and  occurs  also  in 
certain  urinary  calculi. 

The  origin  of  the  oxalic  acid  in  the  urine  is  not  well  known. 
Oxalic  acid,  when  administered,  is  eliminated  by  the  urine  un- 
changed, and  as  many  vegetables  and  fruits,  such  as  cabbage,  spin- 
ach, asparagus,  sorrel,  apples,  grapes,  etc.,  contain  oxalic  acid,  it  is 
possible  that  a  part  of  the  oxalic  acid  of  the  urine  originates  directly 
from  the  food.  Another  part  is  certainly  formed  in  the  body  from 
the  proteids  and  fat  or  by  the  incomplete  combustion  of  the  car- 
bohydrates. The  formation  of  oxalic  acid  from  proteids  (or  fat)  is 
inferred  from  the  fact  that  oxalic  acid  is  eliminated  by  the  urine 
after  food  consisting  entirely  of  flesh  and  fat,  as  also  in  starvation. 
It  has  also  been  considered,  but  without  sufficient  reason,  that  the 
oxalic  acid  of  the  urine  is  an  oxidation  product  of  uric  acid. 

An  increased  elimination  of  oxalic  acid  may  occur  in  diabetes. 
The  question  whether  it  may  occur  as  an  independent  disease 
{pxaluria,  oxalic-acid  diathesis)  has  not  been  positively  decided. 

The  properties  and  reactions  of  oxalic  acid  and  calcium  oxalate 
are  well  known.  The  calcium  oxalate  as  a  constituent  of  urinary 
sediments  will  be  described  later. 

Detection  and  quant itat we  estimation  of  oxalic  acid  in  urine. 
The  presence  of  oxalic  acid  in  solution  in  urine  is  determined 


358  PHYSIOLOGICAL   CHEMI8TBT. 

according  to  the  method  suggested  by  Neubauek,  who  treats 
500-600  c.  c.  of  the  urine  with  OaClj  solution,  makes  alkaline  with 
ammonia  and  then  faintly  acid  with  acetic  acid.  After  24  hours 
the  precipitate  is  collected  on  a  small  filter,  washed  with  water, 
treated  with  hydrochloric  acid  (which  leaves  the  uric  acid  undis- 
solved on  the  filter),  and  washed  again  with  water.  The  filtrate, 
including  the  wash-water,  is  treated  with  an  excess  of  ammonia  and 
allowed  to  stand  34  hours.  Calcium  oxalate  separates  as  quadratic 
octahedra.  The  quantitative  estimation  is  performed  after  the 
same  principle.  The  oxalate  is  converted  into  quick-lime  by  heat, 
and  weighed  as  such. 

AUantoin  or  glyoxyldiueeid,  C^HeNiOs  or 

C0\  ,^nrr  A^  ,  occurs  in  the  urine  of  children  withm 

\NH.CO 

the  first  eight  days  after  birth,  and  in  very  small  amounts  also  in 
the  urine  of  grown  persons  (GtUSSEROW,  Zieglbe  and  Heemahn). 
It  is  found  in  rather  abundant  quantities  in  the  urine  of  pregnant 
women  (Gusserow).  Allantoin  has  also  been  found  in  the  urine 
of  sucking  calves  (Wohler),  and  sometimes  in  the  urine  of  other 
animals  (MEissJsfEE).  It  is  also  found  in  the  amniotic  fluid  and 
allantoic  fluid  of  the  cow  (hence  the  name).  Allantoin  is  formed, 
as  above  stated,  by  the  oxidation  of  uric  acid.  The  increased  elim- 
ination of  allantoin  which  Salkowski  observed  in  dogs  after  the 
administration  of  uric  acid  shows  that  the  formation  of  allantoin 
from  uric  acid  in  the  organism  is  not  improbable. 

Allantoin  is  a  colorless  substance  often  crystallizing  in  prisms, 
difficultly  soluble  in  cold  water,  easily  soluble  in  boiling  water  and 
also  in  warm  alcohol,  but  not  soluble  in  cold  alcohol  or  ether.  It 
combines  with  acids,  forming  salts.  A  watery  allantoin  solution 
gives  no  precipitate  with  silver  nitrate  alone,  but  by  the  careful 
addition  of  ammonia  a  white  flocculent  precipitate  is  formed, 
CiHsAgNiOa ,  which  is  soluble  in  an  excess  of  ammonia  and  which 
consists  after  a  certain  time  of  very  small,  transparent  microscopic 
globules.  The  dried  precipitate  contains  40.75^  silver.  A  watery 
allantoin  solution  is  precipitated  by  mercuric  nitrate. 

Allantoin  is  most  easily  prepared  by  the  oxidation  of  uric  acid 
with  lead  peroxide.  In  preparing  allantoin  from  calves'  urine,  con- 
centrate the  uriue  on  the  water-bath  to  a  syrup  and  allow  it  to 
stand  in  the  cold  for  several  days.     The  crystals  which  are  sepa- 


THE  URINE.  .359 

rated  from  the  precipitate  by  washing  are  dissolved  in  boiling 
water  with  the  addition  of  some  animal  charcoal,  and  filtered  while 
hot ;  then  acidify  the  filtrate  faintly  with  hydrochloric  acid  (so  as 
to  keep  the  phosphates  in  solution)  and  allow  it  to  crystallize.  Al- 
lantoin  is  detected  in  human  urine  by  the  method  first  suggested 
by  Meissner.  It  consists  chiefly  of  the  following  points:  Pre- 
cipitate the  urine  with  baryta- water,  filter,  remove  the  baryta  with 
sulphuric  acid,  filter,  precipitate  the  allantoin  with  HgClj  in  alka- 
line solution,  decompose  the  precipitate  with  sulphuretted  hydro- 
gen, concentrate  strongly,  purify  the  crystals  which  separate  by 
recrystallization,  and  lastly  prepare  the  silver  combination. 

Xanthin  Bodies.  The  xanthin  bodies  which  habitually  occur 
in  human  urine  are  xanthin,  hypoxanthin  (Salomon),  guanin 
(Pouchet),  carnin  (Pouchet),  and  the  newly-discovered  bodies 
paraxantliin  (Thudichum,  SALOiiojsr)  and  heteroxanthin  (Salo- 
Mox).  The  quantity  of  these  bodies  in  the  urine  is  very  small. 
The  quantity  of  xanthin  bodies  in  the  urine  is  increased  especially 
in  leucaemia,  in  which  disease  adenin  is  also  found  in  the  urine 
(Stadthagen).  Xanthin  also  occurs  as  a  constituent  of  a  variety 
of  rare  calculi  (Maecet).  It  is  also  sometimes  found  as  a  constitu- 
ent of  urinary  sediments  (Bejtce  Jones). 

Paraxanthin,  07H8]Sr402  (dimethylxautbin),  and  heteroxanthin,  C6H6N4O2 
(methylxautliia),  do  not  give  the  xanthin  reaction  with  nitric  acid  and  alkali, 
but  give  Weidel's  reaction  (see  page  50).  They  differ  from  other  xanthin 
bodies  by  forming  crystalline  combinations  with  alkalies,  which  are  diffi- 
cultly soluble.  Amorphous  heteroxanthin  separates  on  neutralizing  the  so- 
dium combination,  but  paraxanthin,  on  the  contrary,  separates  in  a  crystalline 
condition.  Paraxanthin  gives  an  easily-soluble  combination  with  hj'dro- 
chloric  acid,  while  heteroxanthin  forms  an  insoluble,  beautiful  crystalline 
combination. 

In  preparing  xanthin  bodies  from  the  urine,  it  is  supersaturated  with 
ammonia  and  precipitated  by  a  silver-nitrate  solution.  The  precipitate  is 
then  decomposed  with  sulphuretted  hydrogen.  The  boiling-hot  filtrate  is 
evaporated  to  dryness  and  the  dried  residue  treated  with  Z%  sulphuric  acid. 
The  xanthin  bodies  are  dissolved,  while  the  uric  acid  remains  undissolved. 
This  filtrate  is  saturated  with  ammonia  and  precipitated  by  silver-nitrate  solu- 
tion. The  different  xanthin  bodies  may  be  separated  from  each  other  by 
treating  the  silver  precipitate  with  boiling-hot  nitric  acid  of  a  sp.  gr.  of  1.1 
(see  page  51). 

Hippuric  acid,  or  benzoyl -amido  acetic  acid,  C9H9NO3  or 
CeHs.CO.NH.CHj.COOH.  This  acid  decomposes  into  benzoic  acid 
and  glycocoll  on  boiling  the  urine  with  mineral  acids  or  alkalies, 
this  also  takes  place  in  putrefaction.  The  reverse  of  this  occurs 
if  these  two  components  are  heated  in  a   sealed  tube,  according 


360  PHYSIOLOGICAL   CHEMISTRY. 

to  the  following  equation:  CeHjCOOH  +  NH2.CH2.COOH  = 
C6H5.CO.NH.CH2.COOH  +  H2O.  This  acid  may  be  synthetically 
prepared  from  benzamid  and  monochlor-acetic  acid,  CcHs.CO.NHg 
+  CH2CI.COOH  =  C6H5.CO.NH.CH2.COOH  +  HOI,  also  in  other 
different  ways. 

Hippuric  acid  occurs  in  large  amounts  in  the  urine  of  herbivora, 
but  only  in  small  quantities  in  that  of  carnivora.  The  quantity  of 
hippuric  acid  eliminated  in  human  urine  on  a  mixed  diet  is  usually 
less  than  1  grm.  per  24  hours;  as  an  average  it  is  0.7  grm.  After 
eating  freely  of  vegetables  and  fruit,  especially  such  fruit  as  plums, 
the  quantity  may  be  more  than  2  grms.  Hippuric  acid  is  also 
found  in  the  perspiration,  blood,  suprarenal  capsule  of  oxen,  and  in 
the  ichthyosis  scales.  Nothing  is  positively  known  in  regard  to  the 
quantity  of  hippuric  acid  in  the  urine  in  disease. 

The  Formation  of  Hippuric  Acid  in  the  organism.  Benzoic  acid 
and  also  the  substituted  benzoic  acids  are  converted  into  hippuric 
acid  and  substituted  hippuric  acids  within  the  body.  Also,  those 
bodies  are  transformed  into  hippuric  acid  which  by  oxidation 
(toluol,  cinnamic  acid,  hydrocinnamic  acid)  or  by  reduction  (quinic 
acid)  are  converted  into  benzoic  acid.  The  question  of  the  origin 
of  hippuric  acid  is  therefore  connected  with  the  question  of  the 
origin  of  benozic  acid;  for  the  formation  of  the  second  component, 
glycocoll,  from  the  protein  substances  in  the  body  is  without  ques- 
tion. 

Hippuric  acid  is  found  in  the  urine  of  starving  human  beings 
(Schultzbn)  and  dogs  (Salkowski),  also  in  dog's  urine  after  a 
diet  consisting  entirely  of  meat  (Meissi^er  and  Shepard,  Salkow- 
ski, and  others).  It  is  evident  that  the  benzoic  acid  originates  in 
these  cases  from  the  proteids.  Benzoic  acid  may  indeed  be  pro- 
duced outside  of  the  body  by  the  oxidation  of  the  albumins;  the 
benzoic  acid  produced  on  a  diet  consisting  entirely  of  meat  seems 
to  be  derived  from  the  putrefaction  of  the  proteids  in  the  intestines. 
Among  the  products  of  the  putrefaction  of  albumin  outside  of  the 
body  Salkowski  has  found  phenyl  propionic  acid,  CeH5.CH2.OH2. 
COOH,  which  is  oxidized  in  the  organism  to  benzoic  acid  and 
eliminated  as  hippuric  acid  after  combining  with  glycocoll.  Phenyl- 
propionic  acid  seems  to  be  formed  from  the  amidophenylpropionic 
acid,  which  is  prepared  only  from  the  plant  proteids,  and  the  sup- 


THE   URINE.  361 

position  that  the  phenylpropionic  acid  is  produced  from  tyrosin  by 
putrefaction  in  the  intestines  has  not  been  substantiated  by  the 
researches  of  Baumaxx,  Schotten  and  Baas.  The  importance 
of  putrefaction  in  the  intestines  in  producing  hippuric  acid  is  evi- 
dent from  the  fact  that  after  thoroughly  disinfecting  the  intestines 
of  dogs  with  calomel  the  hippuric  acid  disappears  from  the  urine 
(Baumanx). 

The  large  quantity  of  hippuric  acid  present  in  the  urine  of  her- 
bivora  is  partly  explained  by  the  fact  that  vegetable  proteids  yield 
perhaps  larger  amounts  of  amidophenylpropionic  acid,  and  partly 
by  the  specially  active  processes  of  putrefaction  going  on  in  the 
intestines  of  herbivora.  These  circumstances  do  not  entirely  ex- 
plain this  excess  of  hippuric  acid  (Salkowski).  The  abundant 
elimination  of  hippuric  acid  by  herbivora  may  in  part  depend  on 
the  great  amount  of  aromatic  substances  in  the  food  of  these  ani- 
mals which  is  converted  into  benzoic  acid.  There  is  hardly  any 
doubt  that  the  hippuric  acid  in  human  urine  after  a  mixed  diet, 
and  especially  after  a  diet  of  vegetables  and  fruits,  has  in  part  a 
similar  origin. 

The  kidneys  may  be  considered  in  dogs  as  special  organs  for 
the  synthesis  of  hippuric  acid  (Schmiedeberg  and  Bunge).  In 
other  animals,  as  in  rabbits,  the  formation  of  hippuric  acid  seems 
to  take  place  in  other  organs,  such  as  the  liver  and  muscles.  The 
synthesis  of  hippuric  acid  is  therefore  not  exclusively  limited  to  any 
special  organ,  though  perhaps  in  some  species  of  animals  it  may  be 
more  abundant  in  one  organ  than  in  another. 

Properties  and  reactions  of  hippuric  acid.  This  acid  crystallizes 
in  semi-transparent,  milk-white,  long,  four-sided  rhombic  prisms  or 
columns,  or  in  needles  by  rapid  crystallization.  They  dissolve  in 
600  parts  cold  water,  but  more  easily  in  hot  water.  They  are  easily 
soluble  in  alcohol,  but  with  difficulty  in  ether.  They  are  more 
easily  soluble  (about  13  times)  in  acetic  ether  than  in  ethyl  ether. 
Petroleum  ether  does  not  dissolve  them. 

On  heating  hippuric  acid  it  first  melts  to  an  oily  liquid  which 
crystallizes  on  cooling.  By  continuing  the  heat  it  decomposes,  pro- 
ducing a  red  mass  and  a  sublimate  of  benzoic  acid,  with  the  genera- 
tion, first,  of  a  peculiar  pleasant  odor  of  hay,  and  then  an  odor  of 
hydrocyanic  acid.     Hippuric  acid  is  easily  differentiated  from  ben- 


362  PHT8I0L001CAL  CHEMISTRY. 

zoic  acid  by  tliis  beliavior,  also  by  its  crystalline  form  and  its  in- 
solubility in  petroleum  ether.  Hippuric  acid  and  benzoic  acid 
both  give  Lijcke's  reaction,  namely,  they  generate  an  intense  odor 
of  nitrobenzol  when  evaporated  with  nitric  acid  to  dryness  and 
when  the  residue  is  heatedi  Hippuric  acid  forms  crystallizable 
salts,  in  most  cases,  with  bases.  The  combinations  with  alkalies 
and  alkaline  earths  are  soluble  in  water  and  alcohol.  The  silver, 
copper,  and  lead  salts  are  soluble  with  difficulty  in  water;  the  iron- 
oxide  salt  is  insoluble. 

Hippuric  acid  is  best  prepared  from  the  fresh  urine  of  a  horse 
or  cow.  The  urine  is  boiled  a  few  minutes  with  an  excess  of  milk 
of  lime.  The  liquid  is  filtered  while  hot,  concentrated  and  then 
cooled,  and  the  hippuric  acid  precipitated  by  the  addition  of  an 
excess  of  hydrochloric  acid.  The  crystals  are  pressed,  dissolved  in 
milk  of  lime  by  boiling,  and  treated  as  above;  the  hippuric  acid  is 
precipitated  again  from  the  concentrated  filtrate  by  hydrochloric 
acid.  The  crystals  are  purified  by  recrystallization  and  decolorized, 
when  necessary,  by  animal  charcoal. 

The  quantitative  estimation  of  hippuric  acid  in  the  urine  may 
be  performed  by  the  following  method  (Bunge  and  Schmieden 
bekg)  :  The  urine  is  first  made  faintly  alkaline  with  soda,  evapo- 
rated nearly  to  dryness,  and  the  residue  thoroughly  exti-acted  with 
strong  alcohol.  After  the  evaporation  of  the  alcohol,  dissolve  in 
water,  acidify  with  sulphuric  acid,  and  completely  extract  by  agitat- 
ing (at  least  five  times)  with  fresh  portions  of  acetic  ether.  The 
acetic  ether  is  then  repeatedly  washed  with  water,  which  is  removed 
by  means  of  a  -separatory  funnel,  then  evaporated  at  a  medium 
temperature,  and  the  dry  residue  treated  repeatedly  with  petroleum 
ether,  which  dissolves  the  benzoic  acid,  oxyacids,  fat  and  phenol, 
while  the  hippuric  acid  remains  undissolved.  This  residue  is  now 
dissolved  in  a  little  warm  water  and  evaporated  at  50°-60°  0.  to 
crystallization.  The  crystals  are  collected  on  a  small  weighed 
filter.  The  mother-liquor  is  repeatedly  shaken  with  acetic  ether. 
This  last  is  removed  and  evaporated;  the  residue  is  added  to  the 
above  crystals  on  the  filter,  dried  and  weighed. 

Phenaceturic  Acid,  CoHnNOg  =  CeHsCH^.CO.NH.CH^.COOH.  This 
acid,  which  is  produced  in  the  animal  body  by  a  grouping  of  the  phenyl- 
acetic  acid,  CeHs.CHs.COOH,  formed  by  the  putrefaction  of  the  proteids 
with  glycocoll,  has  been  prepared  from  horse's  urine  by  Salkowski,  but  it 
probably  also  occurs  in  human  urine. 

Benzoic  Acid,  C7H6O2  or  CeHs.COOH,  is  found  in  rabbit's  urine  and  some- 
times, though  in  small  amounts,  in  dog's  urine  (Weyl  and  v.  Anrep).  Ac- 
cording to  Jaarsveld  and  Stokvis  and  to  Kronecker,  it  is  also  found  in 
human  urine  in  diseases  of  the  kidneys.     The  occurrence  of  benzoic  acid  in 


THE  URINE.  363 

the  urine  seeras  to  be  due  to  a  fermentative  decomposition  of  hippuric  acid. 
Such  a  decomposition  may  very  easily  occur  in  an  alkaline  urine  or  one  con- 
taining albumin  (Van  de  Velde  and  STOK^as).  In  certain  animals — pigs 
and  dogs — the  kidneys,  according  to  Schmiedeberg  and  Minkowski,  contain 
a  special  enzyme,  Schmiedeberg's  histozym,  which  splits  the  hippuric  acid 
with  the  separation  of  benzoic  acid. 

Ethereal  Sulphuric  Acids.  Phenol,  whose  mother-substance  is 
considered  to  be  tyrosin,  is  produced  by  the  putrefaction  of  albumin 
in  the  intestines;  iudol  and  skatol  are  also  produced.  The  phenol 
and  the  two  last-mentioned  bodies,  after  they  have  been  oxidized 
into  indoxyl  and  skatoxyl,  pass  into  the  urine  as  ethereal  sulphuric 
acids  after  uniting  with  sulphuric  acid.  The  most  important  of 
these  ethereal  acids  are  phenol-  and  cresol-sulpjitiric  acid — which 
were  formerly  called  phenol-forming  substance  —  iyicloxyl-  and 
skatoxi/I-suljjJiuric  acid.  To  this  group  belong  also  the  pi/rocaie- 
chin-sulphuric  acid,  which  only  occurs  in  very  small  amounts  in 
human  urine,  and  hydrochinon-sulpUuric  acid,  which  appears  in 
the  urine  after  poisoning  with  phenol,  and  perhaps  under  physio- 
logical conditions  other  ethereal  acids  occur  which  have  not  been 
isolated.  The  ethereal  sulphuric  acids  of  the  urine  were  discovered 
and  specially  studied  by  Baumann.  The  quantity  of  these  acids  in 
the  urine  is  small.  The  quantity  of  grouped  sulphuric  acid  per 
twenty-four  hours  is  on  an  average  0.25  grm.,  but  varies  between 
0.094  and  0.630  grm.  The  relationship  of  the  sulphate-sulphuric 
acid  A  to  the  grouped  sulphuric  acid  B  in  health  is  on  an  average 
as  10  :  1,  but  varies  from  6  :  1  and  15  :  1.  After  taking  phenol, 
also  after  increased  putrefaction  within  the  organism,  this  relation- 
ship may  be  essentially  changed  by  an  increased  elimination  of 
ethereal  sulphuric  acids.  The  urine  of  the  horse  is  considerably 
richer  in  ethereal  sulphuric  acids  than  human  urine. 

Phenol-  and  p-Cresol-sulphuric  Acid,  CgH^.O.SOj.OH  and 
C,H,.0.S02.0H.  These  acids  are  found  as  alkali  salts  in  human 
urine,  in  which  also  orthocresol  has  been  detected.  The  quantity 
of  cresol-sulphuric  acid  is  considerably  greater  than  phenol-sul- 
phuric acid.  In  the  quantitative  estimation  the  phenols  set  free 
from  the  two  ethereal  acids  are  determined  together  as  tribrom- 
phenol.  The  quantity  of  phenol  which  is  separated  from  the 
ethereal  sulphuric  acids  of  the  urine  amounts  to  17-51  milligrammes 
in  the   twenty-four    hours   (Munk).     After  a  vegetable  diet  the 


364  PHYSIOLOGICAL   CHEMISTBT. 

amount  is  greater  than  after  a  meat  diet.  After  taking  carbolic 
acid,  which  is  in  great  part  converted  by  synthesis  within  the  or- 
ganism into  phenol-ethereal  sulphuric  acid,  pyrocatechin-  and 
hydrochinon-sulphuric  acid,  and  also  when  the  amount  of  sulphuric 
acid  is  not  sufficient  to  combine  with  the  phenol  forming  phenyl- 
glycuronic  acid,  the  amount  of  phenol  and  ethereal  sulphuric  acids 
in  the  urine  is  considerably  increased  at  the  expense  of  the  sulphate- 
sulphuric  acid. 

An  increased  elimination  of  phenol-sulphuric  acid  occurs  in 
active  putrefaction  in  the  intestines  with  stoppage  of  the  con- 
tents of  the  intestine,  as  in  ileus,  diffused  peritonitis  with  atonia 
of  the  intestine,  or  tuberculous  enteritis,  but  not  in  simple  ob- 
struction. The  elimination  is  also  increased  by  the  absorption  of 
the  products  of  putrefaction  from  purulent  wounds  or  abscesses. 
An  increased  elimination  of  phenol  has  been  observed  in  a  few 
other  cases  of  diseased  conditions  of  the  body. 

The  alkali  salts  of  phenol-  and  cresol-sulphuric  acids  crystallize 
in  white  plates,  similar  to  mother-of-pearl,  which  are  rather  freely 
soluble  in  water.  They  are  soluble  in  boiling  alcohol,  but  only 
slightly  soluble  in  cold.  On  boiling  with  dilute  mineral  acids  they 
are  decomposed  into  sulphuric  acid  and  the  corresponding  phenol. 

Phenol-sulphuric  acids  have  been  synthetically  prepared  by 
BAUMAi^rN"  from  potassium  pyrosulphate  and  phenol-  or  p-cresol-po- 
tassium.  For  the  method  of  their  preparation  from  urine,  which  is 
rather  complicated,  the  reader  is  referred  to  other  text-books.  The 
quantitative  estimation  of  these  ethereal  sulphuric  acids  is  done  by 
Baltmank  and  Briegee,  by  determining  the  amount  of  phenol 
which  may  be  separated  from  the  urine  as  tribromphenol.  In  this 
determination,  when  the  urine  is  not  specially  rich  in  phenol,  about 
one  fourth  of  the  total  quantity  in  the  twenty-four  hours  is  used; 
it  is  acidified  with  concentrated  hydrochloric  acid — 5  c.  c.  for  every 
100  c.  c.  of  urine — and  distilled  until  a  portion  of  the  distillate 
does  not  give  the  slighest  reaction  for  phenol  with  Millon's  re- 
agent or  with  bromine-water.  The  distillate  is  now  carefully  neu- 
tralized with  soda  solution  (which  combines  with  the  benzoic  acid, 
etc.)  and  again  distilled  until  a  portion  of  the  distillate  is  free  from 
phenol,  as  shown  by  the  above-mentioned  reagents.  This  distillate 
is  treated  with  bromine-water  until  a  permanent  yellow  color  is 
produced,  and  then  allowed  to  stand  for  about  twenty-four  hours 
in  the  cold ;  the  crystalline  precipitate  then  is  collected  on  a  small 


THE   URINE.  365 

weighed  filter,  washed  with  dilute  bromine-water,  dried  over  sul- 
phuric acid  without  the  use  of  a  vacuum  and  weighed  (331  parts 
tribromphenol  correspond  to  94  parts  phenol).  Paracresol  is  gradu- 
ally converted  into  tribromphenol  by  this  treatment  with  bromine- 
water.  The  methods  for  the  separate  determination  of  the  coupled 
sulphuric  acid  and  the  sulphate-sulphuric  acid  will  be  spoken  of 
later  in  connection  with  the  determination  of  the  sulphuric  acid  of 
the  urine. 

PyrocatecMn-sulpliuric  Acid  (and  Pyrocatechin)  .  This  acid  was  first 
found  in  horses'  urine  in  rather  hirge  quantities  by  Baumann.  It  only  occurs 
in  human  urine  in  the  very  smallest  quantities  and  perhaps  not  constantly, 
but  it  occurs  abundantly  in  the  urine  after  taking  phenol,  pyrocatechin,  or 
protocatechinic  acid. 

On  an  exclusive  meat  diet  this  acid  does  not  occur  in  the  urine,  and  it 
therefore  originates  from  the  vegetable  food.  It  probably  originates  from 
the  protocatechuic  acid,  which,  according  to  Preusse,  passes  in  part  into  the 
urine  as  pyrocatechin-sulphuric  acid.  This  acid  may  also  perhaps  depend  ou 
oxidation  of  phenol  within  the  organism  (Bauma>jn  and  Pretjsse). 

Pyrocatechin,  or  o-Dtosybenzol,  C6H4(OH)o,  was  first  obsei-ved  in  the 
urine  of  a  child  (EpsxErrf  and  J.  jMxjller).  The  reducible  body  alcapton, 
first  found  by  Bodeker  in  human  urine  and  which  was  considered  for  a  long 
time  as  identical  with  pyrocatechin,  is  uroleucic  acid,  according  to  Bjrk. 

Pyrocatechin  crystallizes  in  prisms  which  are  soluble  in  alcohol,  ether, 
and  water.  It  melts  at  10"3°-104'  C.  and  sublimes  in  shining  plates.  The 
watery  solution  becomes  green,  brown,  and  ultimately  black  in  the  presence 
of  alkali  and  the  oxygen  of  the  air.  If  very  dilute  ferric  chloride  is  treated 
with  tartaric  acid  and  then  made  alkaline  with  ammonia  and  this  added  to  a 
watery  solution  of  pyrocatechin,  we  obtain  a  violet  or  cherry-red  liquid  which 
becomes  green  b)'  saturating  with  acetic  acid.  Pyrocatechin  is  precipitated 
by  lead  acetate.  It  reduces  an  ammoniacal  silver  solution  at  the  ordinary 
temperature  and  reduces  alkaline  copper-oxide  solutions  with  heat,  but  does 
not  reduce  bismuth  oxide. 

A  urine  containing  pyrocatechin,  if  exposed  to  the  air,  especially  when 
alkaline,  quickly  becomes  dark  and  reduces  alkaline  copper  solutions  with 
heat.  In  detecting  pyrocatechin  in  the  urine  it  is  concentrated  when  necessary, 
filtered,  boiled  with  the  addition  of  sulphuric  acid  to  remove  the  phenols,  and 
repeatedly  shaken  after  cooling  with  ether.  The  ether  is  distilled  from  the 
several  ethereal  extracts,  the  residue  neutralized  with  barium  carbonate  and 
shaken  again  with  ether.  The  pyrocatechin  which  remains  after  evaporating 
the  ether  may  be  purified  by  recrystallization  from  benzol. 

Hydrochinon,  or  p-Dioxybenzol,  CsHjIOIDq,  often  occurs  in  the  urine 
after  the  use  of  phenol  (Baumann  and  Preusse).  The  dark  color  which  cer- 
tain urines,  so-called  "  carbolic  urines,"  take  in  the  air  is  due  to  decomposition 
products.  Hydrochinon  does  not  occur  as  a  normal  constituent  of  urine,  but 
after  the  administration  of  hydrochinon  ;  according  to  v.  JVIering  and  Lewin, 
it  passes  into  the  urine  of  rabbits  as  ethereal  sulphuric  acid,  as  a  decomposition 
product  of  arbutin. 

Hydrochinon  forms  rhombical  crystals  which  are  readily  soluble  in  water, 
alcohol,  and  ether.  It  melts  at  169'  C.  Like  pyrocatechin.  it  easily  reduces 
metallic  oxides.  It  acts  like  pyrocatechin  with  alkalies,  but  is  not  precipitated 
with  lead  acetate.  It  is  oxidized  into  chinon  by  ferric  chloride  and  other 
oxidizing  agents,  and  chinon  is  detected  by  its  peculiar  odor.  Hydrochinon- 
Bulphnric  acid  is  detected  in  the  urine  by  the  same  methods  as  pyrocatechin 
sulphuric  acid. 


366  PHTSIOLOOICAL   CHEMISTRY. 

Indoxyl-sulphuric  acid,  CgH^NSO,  or  CgHgN.O.SOs.OH,  also 
called  UEiKE  in"dican",  formerly  called  ueoxanthin  (Heller), 
occurs  as  alkali-salt  in  the  urine.  This  compound  is  the  mother- 
substance  of  a  great  part  of  the  indigo  of  the  urine.  The  quantity 
of  indigo  which  can  be  separated  from  the  urine  is  considered  as  a 
measure  of  the  quantity  of  indoxyl-sulphuric  acid  (and  indoxyl- 
glycuronic  acid)  contained  in  the  urine.  This  amount,  according 
to  Jaffe,  for  man  is  5-20  milligrammes  per  24  hours.  Horse's 
urine  contains  about  25  times  as  much  indigo-forming  substance  as 
human  urine. 

Indoxyl-sulphuric  acid  is  derived,  as  above  mentioned  (page  21 6), 
from  indol,  which  is  first  oxidized  in  the  body  into  indoxyl  and 
then  is  coupled  with  sulphuric  acid.  After  subcutaneous  injection 
of  indol  the  elimination  of  indican  is  considerably  increased 
(Jaffe,  Baumann  and  Brieger).  It  is  also  increased  by  the 
introduction  of  orthonitrophehylpropiolic  acid  in  the  organism  of 
animals  (Gr.  Hoppe-Setler).  Indol  is  formed  by  the  putrefaction 
of  proteids,  and  it  is  therefore  easy  to  understand  why  the  quantity 
of  indoxyl-sulphuric  acid  is  greater  with  a  meat  than  with  a  vege- 
table diet.  The  putrefaction  of  secretions  rich  in  albumin  in  the 
intestine  explains  also  the  occurrence  of  indican  in  the  urine 
during  starvation.  Gelatine,  on  the  contrary,  does  not  increase  the 
elimination  of  indican.  An  abnormally-increased  elimination  of 
indican  occurs  in  such  diseases  as  obstruct  the  small  intestine, 
causing  an  increased  putrefaction,  thus  producing  an  abundant 
formation  of  indol.  Such  an  increased  elimination  of  indican 
occurs  on  tying  the  small  intestine  of  a  dog,  but  not  the  large 
intestine  (Jaffe). 

The  simple  obstruction  of  the  human  colon  does  not  increase 
the  indican  in  the  urine.  The  obstruction  of  the  large  intestine 
may,  when  it  causes  a  considerable  disturbance  in  the  motion  of 
the  contents  of  the  upper  ileum,  produce  an  increased  elimination 
of  indican.  Like  the  putrefaction  in  the  intestine,  the  putrefaction 
of  proteids  in  other  organs  and  tissues  of  the  body  may  cause  an 
increase  in  the  indican  of  the  urine. 

An  increased  elimination  of  indican  has  been  observed  in  many 
diseases,  such  as  in  ileus,  cholera,  acute  general  peritonitis,  abscess, 
and  carcinoma  of  the  stomach,  intestinal  catarrh,  multiple  lym- 


THE  URINE.  367 

pnoma,  fetid  bronchitis,  ichorous  pleural  exudations,  diabetes 
mellitus,  and  others.  The  increase  of  indican  in  the  urine  observed 
in  consumption  and  inanition  depends  probably  upon  the  disturbed 
digestion.  In  increased  elimination  of  indican  the  elimination  of 
phenol  is  also  increased  ;  a  urine  rich  in  phenol  is,  on  the  contrary, 
not  always  rich  in  indican. 

The  potassium-salt  of  indoxyl-sulphuric  acid  which  was  pre- 
pared by  Baumann  and  Beieger  from  the  urine  of  a  dog  fed  on 
indol,  crystallizes  in  colorless,  shining  plates  or  leaves  which  are 
easily  soluble  in  water  but  less  readily  in  alcohol.  It  is  split  by 
mineral  acids  into  sulphuric  acid  and  indoxyl.  The  latter  without 
access  of  air  passes  into  a  red  compound,  indoxyl-red,  but  in  the 
presence  of  oxidizing  reagents  is  converted  into  indigo-blue : 
2C8H7NO  +  20  =  C16H10N2O2  +  2H2O.  The  detection  of  indican 
is  based  on  this  last  fact. 

For  the  rather  complicated  preparation  of  indoxyl-sulphuric 
acid  as  potassium-salt  from  urine  the  reader  is  referred  to  other 
text-books.  For  the  detection  of  indican  in  urine  in  ordinary  cases 
the  following  method  of  Jaffe,  which  also  serve  as  an  approximate 
test  for  the  quantity  of  indican,  is  sufficient. 

Jaffe's  Indican  Test.  20  c.  c.  of  urine  are  treated  in  a  glass 
with  2-3  c.  c.  chloroform  and  mixed  with  an  equal  volume  of 
concentrated  hydrochloric  acid.  Immediately  after  a  concentrated 
chloride-of-lime  solution  or  a  ^fo  potassium-permanganate  solution  is 
added  drop  by  drop,  and  after  each  drop  the  mixture  is  thoroughly 
shaken.  The  chloroform  is  gradually  colored  faintly  or  strongly 
blue.  An  excess  of  oxidizing  reagent,  especially  chloride  of  lime, 
interferes  with  the  reaction  and  must  therefore  be  avoided.  The 
test  is  repeated  with  somewhat  varying  amounts  of  oxidizing 
material  until  a  point  is  found  at  which  the  maximum  coloration  of 
the  chloroform  takes  place.  From  the  intensity  of  the  color  the 
quantity  of  indigo  is  determined. 

An  exact  determination  of  the  amount  of  indigo  in  urine  is  very 
rarely  made.  The  methods  suggested  for  this  purpose  are  very 
complicated,  and  even  then  they  are  not  quite  accurate;  therefore 
the  reader  is  referred  to  other  text-books  for  their  description. 

Indol  seems  also  to  pass  into  the  urine  as  a  glycuronic  acid, 
indoxyl- glyciironic  acid  (Schmiedeberg).  Such  an  acid  has  been 
found  in  the  urine  of  animals  after  the  administration  of  the 
sodium-salt  of  o-nitrophenylpropiolic  acid  {Gf.  Hoppe-Seyler). 


/ 


368  PHYSIOLOGICAL   CHEMISTRY. 

Skatoxyl-sulphuric  Acid,  C9H9NSO,  or  CgHg.N.O.SO^.OH.  The 
potassinm-salt  of  this  acid  seems  to  occur  generally  in  human  urine 
as  a  chromogen,  which  yields  a  red  or  violet  coloring  matter  on  de- 
composing with  strong  acids,  and  an  oxidizing  reagent.  This  salt 
has  been  prepared  by  Otto  from  diabetic  human  urine.  Little  is 
known  of  the  quantity  of  this  skatolchromogen,  to  which  probably 
also  the  skatoxyl-glycuronic  acid  must  be  counted,  under  physiol- 
ogical and  pathological  conditions. 

Skatoxyl-sulphuric  acid  originates  from  skatol  formed  by  putre- 
faction in  the  intestine,  which  is  coupled  with  sulphuric  acid  after 
oxidation  into  skatoxyl.  That  skatol  introduced  into  the  body 
passes  partly  as  an  ethereal  sulphuric  acid  into  the  urine  has  been 
shown  by  Brieger.  Indol  and  skatol  act  differently,  at  least  in 
dogs;  indol  producing  a  considerable  amount  of  ethereal  sulphuric 
acid,  while  skatol  only  gives  a  small  quantity  (Mester).  Skatol 
seems  partly  to  pass  into  the  urine  as  a  skatoxyl-glycuronic  acid. 

The  potassium-salt  of  skatoxyl-sulphuric  acid  is  crystalline;  it 
dissolves  in  water,  but  with  difficulty  in  alcohol.  A  watery  solution 
becomes  deep  violet  with  ferric  chloride,  and  red  with  concentrated 
nitric  acid.  The  salt  is  decomposed  by  concentrated  hydrochloric 
acid  with  the  separation  of  a  red  precipitate.  The  nature  of  this 
red  coloring  matter  produced  by  the  decomposition  of  skatoxyl- 
sulphuric  acid  is  not  well  known;  neither  is  the  relationship  exist- 
ing between  this  and  other  red  coloring  matters  in  the  urine  known. 
On  distillation  with  zinc-dust  the  skatol  coloring  matter  yields 
skatol. 

Urines  containing  skatoxyl  are  colored  dark  red  to  violet  by 
Jaffb^s  indican  test  even  after  the  addition  of  hydrochloric  acid; 
with  nitric  acid  they  are  colored  cherry-red,  and  on  warming  with 
ferric  chloride  and  hydrochloric  acid  red.  The  coloring  matter 
which  yields  skatol  with  zinc-dust  may  be  removed  from  the  urine 
by  ether.  Urines  rich  in  skatoxyl  darken  when  allowed  to  stand, 
and  may  become  reddish,  violet,  or  nearly  black. 

Salkowski  has  shown  that  the  occurrence  of  skatol-carhonic  acid,  CgHe. 
N.COOH,  in  normal  urine  is  probable.     This  is  also  a  putrefaction  product. 

Aromatic  Oxyacids.  In  tlie  putrefaction  of  proteids  in  the 
intestine,  paraoxyphenyl-acetic    acid,    CfiHi(0H).CH2C00H,  and 


THE   URINE.  369 

paraoxypJienyl-propionic  acid,  C6H4(OH).C2H4.COOH,  are  formed 
from  tyrosin  as  intermediate  steps,  and  tliese  pass  unchanged  into 
the  urine.  They  were  first  detected  by  Baumann.  The  quantity 
of  these  acids  is  usually  very  small.  They  are  increased  by  the 
same  circumstances  as  phenol,  especially  in  acute  phosphorus-poi- 
soning, in  which  the  increase  is  considerable.  In  acute  atrophy  of 
the  liver  another  oxyacid,  oxymandel-acid,  has  been  found  in  the 
urine  (Schultzen  and  Eiess). 

The  above  two  acids  are  soluble  in  ether.  On  warming  with  Millon's 
reagent  they  give  a  beautiful  red  color.  To  detect  the  presence  of  these  oxy- 
acids  proceed  in  the  following  way  (Baumann)  :  Warm  the  urine  for  a  while 
on  the  water-bath  with  hydrochloric  acid,  in  order  to  drive  off  the  volatile 
phenols.  After  cooling  shake  three  times  with  ether,  and  then  shake  the 
ethereal  extracts  with  dilute  soda  solution,  which  dissolves  the  oxyacids,  while 
the  residue  of  the  phenols  soluble  in  ether  remains.  The  alkaline  solution  of 
the  oxyacids  is  now  faintly  acidified  with  sulphuric  acid,  shaken  again  with 
ether,  the  ether  removed  and  allow  to  evapoiate,  the  residue  dissolved  in  a 
little  water,  and  the  solution  tested  with  Millon's  reagent.  The  two  oxyacids 
are  best  differentiated  by  their  different  melting-poiuts.  The  reader  is  referred 
to  other  works  for  the  method  of  isolating  and  separating  these  two  oxyacids. 

Uroleucic  Acid,  C^HjoOs.  This  acid  in  a  pure  state  was  first  prepared  by 
Marshall  from  urine,  but  named  and  specially  studied  by  Kikk.  In  an  im- 
pure state  it  forms  the  reducible  substance  alcapton  discovered  by  Boede- 
KER.  This  acid  is  especially  found  in  children's  urine.  Such  urine  reduces 
Fehling's  reagent,  but  not  an  alkaline  bismuth  or  picric-acid  solution.  It  is 
fermentable,  optically  inactive,  and  is  colored  deep  brown  in  the  air,  espe- 
cially in  an  alkaline  solution.  In  these  respects  it  differs  from  a  urine  con- 
taining sugar. 

Urinary  Coloring  Matters  and  Chromogens.  The  yellow  color  of 
normal  urine  depends  apparently  upon  several  coloring  matters 
(Vieeoedt)  which  have  not  been  isolated  and  studied.  Besides 
these  bodies,  urobilin"  sometimes  occurs  in  fresh  normal  urine,  but ' 
by  no  means  always.  Instead  of  urobilin,  normal  urine  often  con- 
tains a  mother-substance  of  the  same,  a  chromogen  or  urobilinogen, 
from  which  the  urobilin  is  gradually  formed  by  oxidation  on  allow- 
ing the  urine  to  stand  exposed  to  the  air  (Jaffe,  Stokvis,  Disque, 
and  others).  Besides  this  chromogen,  urine  contains  various  other 
bodies  from  which  coloring  matters  may  be  produced  by  the  action 
of  chemical  agents.  Humous  substances  (perhaps  in  part  from  the 
carbohydrates  of  the  urine)  may  be  formed  by  the  action  of  acids 
(v.  Udran"Szky  and  Hoppe-Seyler)  without  regard  to  the  fact 
that  such  substances  may  sometimes  originate  from  the  reagents 
used,  as  from  impure  amyl-alcohol  (v.  Udran'Szky  and  Hoppe- 


370  PEY810L00ICAL  CHEMISTRY, 

Seyler).  To  these  humin  bodies  developed  by  the  action  of  acid 
in  normal  urine  when  exposed  to  the  air  must  be  added  the 
UROPHAiN  of  Heller,  the  various  UEOMELAiii'iNS,  and  other 
bodies  described  by  different  investigators  (Plos'z,  Thudichum, 
ScHUifCK).  Indigo-blue  (uroglaucin  of  Heller,  urocyanin, 
CYANURiisr,  and  other  coloring  matters  of  older  investigators)  is 
split  off  from  the  indoxyl-sulphuric  acid  or  indoxyl-glycuronic  acid. 
Eed  coloring  matters  may  be  formed  from  the  coupled  indoxyl 
and  skatoxyl  acids,  and  urohodin"  (Heller),  urorubin  (Plos'z), 
UEOH^MATiN"  (Harley),  and  perhaps  also  urorosbin  (Nencki 
and  Sieber)  probably  have  such  an  origin. 

We  cannot  enter  into  too  many  details  of  the  different  coloring 
matters  obtained  as  decomposition  products  from  normal  urine; 
and  as  the  preformed  physiological  coloring  matters  of  urine  have 
not  been  closely  studied,  we  can  only  discuss  the  most  carefully- 
investigated  urinary  pigment,  urobilin. 

Urobilin  was  first  prepared  from  urine  by  Jaffe.  This  color- 
ing matter  occurs  in  urine  especially  in  fevers,  and  it  is  therefore 
designated  febrile  urobilin  by  MacMunn.  The  urobilin 
occurring  in  normal  urine  is  somewhat  different  from  an  optical 
standpoint  from  the  above,  and  is  called  normal  urobilin  by 
MacMunn.  As  above  stated,  a  mother-substance  of  urobilin,  a 
urobilinogen,  occurs  in  the  urine,  from  which  urobilin  is  pro- 
duced by  the  action  of  the  air. 

Many  investigators  claim  that  urobilin  is  identical  with  hydro- 
bilirubin  (Maly)  and  corresponds  to  the  composition  CggHioN^OT. 
Also,  that  urobilin  is  formed  by  a  reduction  of  bilirubin  in  the 
intestine.  The  correctness  of  this  view  is  disputed  by  others 
(MacMunn,  Le  ISTobel).  According  to  MaoMunn,  hydrobiliru- 
bin  and  the  urinary  urobilin  are  not  identical  bodies,  because  he 
obtained  normal  urobilin  by  the  action  of  peroxide  of  hydrogen 
upon  a  solution  of  hsBmatin  in  alcohol  containing  sulphuric  acid. 

Coloring  matters  similar  to  urobilin,  though  not  identical,  have 
been  obtained  from  the  biliary  and  from  the  blood  coloring  mat- 
ters. Besides  the  hydrobilirubin  prepared  by  Maly  from  bilirubin, 
Stokvis  obtained  a  choletelin  from  a  biliary  pigment,  cholecyanin, 
by  the  action  of  zinc  chloride  and  tincture  of  iodine,  or  by  boiling 


THE   UBINE.  371 

with  a  little  lead  peroxide.  This  choletelin  acts  like  urobiliu,  but 
that  obtained  from  bilirubin  by  the  action  of  nitric  acid  does  not. 
Bodies  similar  to  urobilin  have  also  been  obtained  by  Hoppe- 
Seyler,  by  the  reduction  of  hsematin  and  hgemoglobin  with  zinc  and 
hydrochloric  acid;  by  Le  Nobel,  by  treating  an  acid-alcoholic  or 
alkaline  solution  of  htematoporphyrin  with  tin  or  zinc;  and  lastly 
by  Nencki  and  Sieber,  by  treating  hsematoporphyrin  with  zinc 
and  hydrochloric  acid.  From  the  observations  of  Le  Nobel  and 
Nexcki  and  Sieber  it  follows  that  these  coloring  matters  arti- 
ficially prepared  from  the  blood -coloring  matters  are  not  identical, 
even  though  they  are  closely  related  from  an  optical  standpoint. 
It  must  be  left  undecided  whether  these  bodies  are  identical  with 
each  other  or  with  the  urinary  urobiliu,  or  if  the  observed  difference 
is  only  due  to  a  contamination  with  other  bodies. 

Because  of  our  imperfect  knowledge  of  the  urobilin  of  the  urine 
and  the  urobilinoidin  (this  name  has  been  given  by  Le  Nobel  to 
the  substance  artificially  prepared  by  him)  it  is  difficult  to  say 
anything  positive  in  regai'd  to  the  occurrence  of  urobilin  in  the 
urine  in  disease.  During  the  absorption  of  large  blood  extravasa- 
tions, as  also  in  diseases  connected  with  destruction  of  the  blood- 
corpuscles  or  of  the  appearance  of  methgemoglobin  in  the  blood- 
plasma,  the  urine  becomes  dark  in  color,  which  generally  depends 
upon  an  increased  elimination  of  urobilin.  The  question  whether 
it  depends  on  an  increased  elimination  of  urinary  urobilin  or,  as  is 
more  probable,  upon  the  urobilinoidin  produced  from  the  blood- 
coloring  matters  is  still  doubtful.  In  icterus  the  elimination  of 
urobilin  is  often  increased,  and  indeed  cases  occur  in  which  the 
urobilin  is  almost  the  only  coloring  matter  which  can  be  detected 
in  icteric  urines  (urobilinicterus).  In  these  cases  we  are  probably 
dealing  with  a  urobiliuoid  substance  produced  from  the  bile-coloring 
matters. 

The  urobilin  obtained  from  a  fever  urine  is,  according  to 
Jaffe,  amorphous,  red,  dingy-red,  or  reddish  yellow,  according  to 
the  method  of  preparation.  It  dissolves  easily  in  alcohol,  amyl- 
alcohol,  and  chloroform,  but  less  readily  in  ether.  It  is  less 
soluble  in  water,  but  the  solubility  is  augmented  in  the  presence  of 
a  neutral  salt.     It  may  be  precipitated  from  a  solution  saturated 


372  PHYSIOLOGICAL   CHEMISTET. 

with  ammonmm  sulphate  by  the  addition  of  sulphuric  acid 
(Mehy).  It  is  soluble  in  alkalies  and  is  incompletely  precipitated 
from  the  alkaline  solution  by  the  addition  of  acid.  It  is  partly 
dissolved  by  chloroform  from  an  acid  (watery -alcoholic)  solution ; 
alkali  solutions  remove  the  urobilin  from  the  chloroform.  The 
alkaline  solutions  of  urobilin  give  insoluble  combinations  with  salts 
of  the  heavy  metals,  such  as  zinc  and  lead.  Urobilin  does  not  give 
GtMELIn's  test  for  bile-pigments. 

Neutral  alcoholic  urobilin  solutions  are  in  strong  concentration 
brownish  yellow,  in  great  dilution  yellow  or  rose-colored.  They 
have  a  strong  green  fluorescence.  The  acid-alcoholic  solutions  are,, 
according  to  concentration,  brown,  reddish  yellow,  or  rose-red. 
They  are  not  fluorescent,  but  show  a  faint  absorption-band,  y,. 
between  h  and  F,  which  borders  on  F,  or  in  greater  concentration 
extends  over  F.  The  alkaline  solutions  are,  according  to  concen- 
tration, brownish  yellow,  yellow,  or  (the  ammoniacal)  yellowish 
green.  If  some  zinc-chloride  solution  is  added  to  an  ammoniacal 
solution,  it  becomes  red  and  shows  a  beautiful  green  fluorescence. 
This  solution,  as  also  that  made  alkaline  with  fixed  alkalies,  shows 
a  darker  and  more  sharply-defined  band,  d,  almost  midway  between 
b  and  F. 

The  urobilin  obtained  by  MacMunist  according  to  other 
methods,  and  that  obtained  by  Jaffe,  differ  from  each  other 
mainly  in  the  following:  A  solution  of  normal  urobilin  becomes 
deeper  red  with  soda,  while  the  febrile  urobilin  becomes  yellow. 
The  band  y  of  the  normal  urobilin  disappears  on  the  addition  of 
alkali,  while  the  corresponding  band  of  the  febrile  moves  towards 
the  left.  The  ethereal  solution  of  febrile  urobilin  shows  two  faint 
absorption-bands  on  each  side  of  D  which  are  not  to  be  seen  in  the 
watery  solution  nor  in  the  urine.  Febrile  urobilin  is  a  brownish- 
red  and  the  normal  a  yellowish-brown  powder.  Febrile  urobilin  is, 
according  to  MAcMuN"]sr,  converted  into  normal  urobilin  by  po- 
tassium permanganate. 

In  preparing  urobilin  from  normal  urine,  precipitate  the  urine 
with  basic  lead  acetate  (Jaffe),  wash  the  precipitate  Avith  water, 
dry  at  the  ordinary  temperature,  then  boil  it  with  alcohol,  and 
decompose  it  when  cold  with  alcohol  containing  sulphuric  acid. 
The  filtered  alcoholic  solution  is  diluted  with  water,  saturated  with 


THE  URINE.  373 

ammonia,  and  then  treated  with  zinc-chloride  solution.  This  new 
precipitate  is  washed  free  from  chlorine  with  water,  boiled  with 
alcohol,  dried,  dissolved  in  ammonia,  and  this  solution  precipitated 
with  sugar  of  lead.  This  precipitate,  which  is  washed  with  water 
and  boiled  with  alcohol,  is  decomposed  by  alcohol  containing  sul- 
phuric acid,  the  filtered  alcoholic  solution  is  mixed  with  4  vol. 
chloroform,  diluted  with  water,  and  shaken  repeatedly,  but  not  too 
energetically.  The  urobilin  is  taken  up  by  the  chloroform.  This 
last  is  washed  once  or  twice  with  a  little  water  and  then  filtered, 
leaving  the  urobilin,  which  is  purified  from  a  contaminating  red 
coloring  matter  by  means  of  ether. 

According  to  Jaffe,  the  coloring  matter  can  be  directly  precipitated  from 
a  fever  urine  rich  in  urobilin  by  ammonia  and  zinc  chloride,  and  this  precipi- 
tate treated  as  above.  Mehy  faintly  acidities  the  urine  with  sulphuric  acid 
(1-2  grms.  per  litre),  then  saturates  with  ammonium  sulphate,  washes  the  pre- 
cipitate on  a  filter  with  an  acidified  ammonium-sulphate  solution,  presses  the 
filter,  and  extracts  the  coloring  matter  with  absolute  alcohol  at  a  gentle  heat 
after  the  addition  of  a  few  drops  of  ammonia.  MacMunn  precipitates  the  urine 
with  sugar  of  lead  and  basic  lead  acetate,  decomposes  the  precipitate  with 
acidified  alcohol,  dilutes  the  solution  with  water,  shakes  with  chloroform, 
evaporates  this  last,  and  dissolves  the  residue  repeatedly  with  chloroform. 
The  method  of  preparation,  according  to  MacMunn,  is  the  same  for  both 
urobilins,  the  normal  and  the  febrile. 

The  color  of  the  acid  or  alkaline  solution,  the  beautiful  fluores- 
cence of  the  ammoniacal  solution  treated  with  zinc  chloride,  and 
the  absorption-bands  of  the  spectrum,  all  serve  as  means  of  detect- 
ing urobilin.  In  fever  urines  the  urobilin  may  be  detected  directly 
or  after  the  addition  of  ammonia  and  zinc  chloride  by  its  spectrum. 
It  may  also  be  detected  sometimes  in  normal  urine  directly  or  after 
the  urine  has  stood  exposed  to  the  air  until  the  chromogen  has 
been  converted  into  urobilin.  If  it  cannot  be  detected  by  means  of 
the  spectroscope,  then  the  urine  may  be  treated  with  a  mineral  acid 
and  shaken  with  ether.  The  ethereal  solution  may  be,  directly  or 
after  concentration,  tested  with  the  spectroscope.  It  is  often  bet- 
ter to  dissolve  the  residue,  after  the  evaporation  of  the  ether,  in 
absolute  alcohol,  and  use  this  for  the  spectroscopic  investigation. 
According  to  Salkowski,  the  urobilin  may  be  directly  extracted 
by  gently  shaking  with  ether  free  from  alcohol.  If  the  urobilin 
cannot  be  detected  by  the  above-described  methods,  then  precipi- 
tate the  urine  with  basic  lead  acetate,  decompose  the  jorecipitate 
with  acidified  alcohol,  test  this  solution  or  extract  the  coloring 
matter  by  diluting  with  water  and  shaking  with  chloroform. 

The  vrochrom  (Thudichum)  seems  to  be  a  mixture  of  several  bodies. 
Uroerythrin  is  that  coloring  matter  which  often  colors  the  urinary  sediment 
{sedimentum  lateritium)  beautifully  red.  It  occurs  especially  in  fevers  and 
other  diseases,  but  it  is  not  found  in  the  urine  of  perfectly  healthy  persons. 


374  PHYSIOLOGICAL  CHEMI8TBT. 

Volatile  fatty  acids,  sucli  as  formic  acid,  acetic  acid,  and  perhaps  also 
butyric  acid,  occur  under  normal  conditions  in  human  urine  (v.  Jaksch),  also 
in  that  of  dogs  and  herbivora  (Schotten).  The  acids  poorest  in  carbon, 
formic  acid,  and  acetic  acid  are  more  constant  in  the  body  than  those  richer  in 
carbon,  and  therefore  the  relatively  greater  part  pass  unchanged  into  the  urine 
(Schotten).  Normal  human  urine  contains  besides  these  bodies  others  which 
yield  acetic  acid  when  oxidized  by  potassium  dichromate  and  sulphuric  acid 
(V.  Jaksch).  The  quantity  of  volatile  fatty  acids  in  normal  urine  is,  according 
to  V.  Jaksch,  0.008-0.009  grm.  per  24  hours,  and  according  to  v.  Robitansky, 
0.054  grm.  The  quantity  is  increased  by  exclusive  farinaceous  food,  also  in 
fever  and  in  certain  diseases  of  the  liver  (v.  Jaksch).  It  is  also  increased  iu 
leucaemia  and  in  many  cases  of  diabetes  (v.  Jaksch).  Large  amounts  of 
volatile  fatty  acids  are  produced  in  alkaline  fermentation  of  the  urine,  and  the 
quantity  is  15-16  times  as  large  as  in  normal  urine  (Salkowski). 

Paralactic  Acid.  It  is  claimed  that  this  acid  occurs  in  the  urine  of  healthy 
persons  after  veiy  fatiguing  marches  (Colasanti  and  Moscatelli).  It  is 
found  in  larger  amounts  in  the  urine  in  acute  phosphorus  poisoning  or  acute 
j^ellow  atroph}'-  of  the  liyer  (Schultzen  and  Riess),  also  in  osteomalacia 
(Mors  and  Muck).  After  the  extirpation  of  the  liver  of  birds  it  is  found  in 
large  quantities  in  their  urine  (Minkovs^ski).  Olycero-pJiosphoric  acid  occurs  as 
traces  in  the  urine,  and  it  is  probably  a  decomposition  product  of  lecithin.  The 
occurrence  of  succinic  acid  in  normal  urine  is  the  subject  of  discussion. 

Carhohydrates  and  Reducing  Substances  in  the  Urine.  The 
occurrence  of  grape-sugar  as  traces  in  normal  urine  is  highly  prob- 
able, as  the  investigations  of  Brucke,  Abeles  and  v.  Udranszki 
show.  The  last  has  also  shown  the  habitual  occurrence  of  carbo- 
hydrates in  the  urine,  and  their  presence  has  been  positively  proved 
by  the  investigations  of  Baumanist  and  Wedenski.  Besides  this, 
the  urine  contains  traces  of  a  carbohydrate  similar  to  dextrin 
(animal  gum)  (Landwehr,  Wedenski).  Besides  traces  of  sugar 
and  the  previously-mentioned  reducing  substances,  uric  acid  and 
creatinin,  the  urine  contains  still  other  reducing  substances.  These 
last  are  probably  (Fluckiger)  coupled  combinations  of-  glycuronic 
acid,  CsHioOy,  which  closely  resembles  sugar.  The  reducing  ])ower 
of  normal  urine  corresponds  according  to  Fluckiger  to  1.5-2.5 
p.  m.  grape-sugar,  according  to  Salkowski  4.08,  according  to 
MuNK  an  average  of  3.0,  and  according  to  Worm  Muller  about 
4.0  p.  m. 

Glycuronic  Acid,  OeHioOr  or  OHO.(CH.OH)i.COOH.  This 
acid  may  be  converted  into  saccharic  acid,  CgHioOg ,  by  the  action  of 
bromine  (Thierfelder),  and  it  seems  to  occupy  an  intermediate 
position  between  this  acid  and  gluconic  acid,  CeHigO; ,  obtained  by 
the  oxidation  of  glucose  or  cane-sugar  with  chlorine  or  bromine. 
Glycuronic  acid  probably  only  occurs  normally  in  very  small  quanti- 


TEE  URINE.  375 

ties  in  human  urine  as  coupled  combinations  with  indoxyl,  skatoxyl, 
and  phenols.  It  is  also  found  in  the  artists'  color  "  jaune  indien/' 
which  contains  the  magnesium-salt  of  euxauthonic  acid.  On  heat- 
ing this  acid  with  water  to  120°-135°  C.  it  splits  into  euxanthin  and 
glycuronic  acid. 

This  acid  may  pass  into  the  urine  in  larger  quantities  as  coupled 
glycuronic  acids  after  the  administration  of  various  medicines  or 
other  substances  (see  below).  Thus  after  the  administration  of 
chloral  hydrate,  naphthaliu,  camphor,  and  turpentine,  respectively, 
urochloralic  acid,  naphthol-glycuronic  acid,  campho-glycuronic 
acid,  and  terpen-glycuronic  acid  appear  in  the  urine.  The  coupled 
glycuronic  acids  turn  the  plane  of  polarization  to  the  left,  while 
glycuronic  acid  itself  is  dextro-gyrate.  With  the  absorption  of 
water  they  may  split  into  glycuronic  acid  and  other  coupled  bodies. 
A  few  of  the  coupled  glycuronic  acids,  such  as  the  urochloralic 
acid,  reduce  copper  oxide  and  certain  other  metallic  oxides  in  al- 
kaline solution,  and  therefore  they  may  interfere  with  the  detection 
of  sugar  in  the  urine. 

Glycuronic  acid  is  not  crystalline,  but  is  obtained  only  as  a  syrup. 
It  dissolves  in  alcohol  and  is  easily  soluble  in  Avater.  If  the  watery 
solution  is  boiled  for  an  hour,  the  acid  is  in  part  (20^)  converted 
into  the  anhydride  GLTCUKO]sr,C6H806,  which  is  crystalline,  soluble 
in  water  but  insoluble  in  alcohol.  The  potassium-salt  of  this  acid 
crystallizes  in  fine  needles.  The  neutral  barium-salt  is  amorphous, 
soluble  in  water,  but  is  precipitated  by  alcohol.  If  a  concentrated 
solution  of  the  acid  is  saturated  with  barium  hydrate,  the  basic  ba- 
rium-salt separates.  The  neutral  lead-salt  is  soluble  in  water,  but 
the  basic  salt  is,  on  the  contrary,  insoluble.  The  acid  is  dextro- 
gyrate, reduces  copper,  silver,  and  bismuth  salts.  It  gives  a  crys- 
talline combination  with  phenylhydrazin. 

Glycuronic  acid  maybe  prepared  from  urochloralic  acid  or  cam- 
pho-glycuronic acid  by  boiling  with  a  mineral  acid.  It  may  be 
prepared  more  easily  by  heating  euxanthonic  acid  with  water  in 
Papin's  digester  to  120°-125°  C.  for  an  hour  and  evaporating  the 
watery  solution  at-|-40°  0.  The  anhydride  which' crystallizes  grad- 
ually is  removed,  the  mother-liquor  diluted  with  water  and  boiled 
for  a  time  to  convert  a  second  portion  of  acid  into  anhydride,  and 
then  evaporated  at  about  -|-  40°  C.     This  is  continued  until  nearly 


376  PHYSIOLOGICAL   CHEMISTRY. 

all  the  acid  is  converted  into  anhydride.     The  anhydride  may  then 
he  further  purified. 

Organic  combinations  containing  sulphur  of  unknown  kind,  which  may  in 
small  part  consist  of  sulphocyanides,  0.04  (Gscheidlen)  —  0.11  p.  m.  (J. 
MuNK),  cystin,  or  bodies  related  to  it,  and  protein  bodies,  are  found  in  human 
as  well  as  in  animal  urines.  The  sulphur  of  these  mostly  unknown  combina- 
tions has  been  called  "neutral,"  to  differentiate  it  from  the  "  acid  "  sulphur 
of  the  sulphate  and  ethereal-sulphuric  acids  (Salkowski).  The  neutral  sul- 
phur ia  normal  urine  as  determined  by  Salkowski  is  15^  by  Stadthagen 
13.3-14.5^,  and  by  Lepine  20^  of  the  total  sulphur.  An  increase  in  the  quan- 
tity of  neutral  sulphur  has  been  observed  in  icterus  (Lepine),  and  in  cystin- 
uria  (Stadthagen). 

The  total  quantity  of  sulphur  in  tbe  urine  is  determined  by  fusing  the  solid 
urinary  residue  with  saltpetre  and  caustic  alkali.  The  quantity  of  neutral 
sulphur  is  determined  as  the  difference  between  the  total  sulphur  and  the  sul- 
phur of  the  sulphate  and  ethereal  sulphuric  acids. 

Sulphuretted  hydrogen  occurs  in  urine  only  under  abnormal  conditions  or 
as  a  decomposition  product.  Sulphuretted  hydrogen  may  be  produced  from 
the  neutral  sulphur  of  the  organic  substances  of  the  urine  by  the  action  of 
certain  bacteria  (Fr.  Muller,  Salkowski).  Other  investigators  (Rosenheim: 
and  Gutzmann)  have  given  hyposulphites  as  the  source  of  the  sulphuretted 
hydrogen.  The  occurrence  of  hyposulphites  in  normal  human  urine,  which 
is  asserted  by  Hefpter,  is  disputed  by  Salkowski.  In  cat's  and  dog's  urine 
the  hyposulphites  are,  on  the  contrary,  constant. 

Organic  combinations  containing  phosphorus  (glycero-phosphoric  acid,  etc.), 
which  yield  phosphoric  acid  on  fusing  with  saltpetre  and  caustic  alkali,  are 
also  found  in  urine  (Zulzeb,  Lepine,  Eyronnet,  and  Aubert). 

Enzymes  of  various  kinds  have  been  isolated  from  the  urine.  Among  these 
we  may  mention  pepsin  (Brucke  and  others),  diastatic  enzyme  (Cohnheim  and 
others),  and  rennet  (Grutzner,  Holovtschiner,  Helwes).  The  occurrence 
of  trypsin  in  the  urine  is  doubtful. 

Substances  similar  to  mucin  (nucleoalbumin  ?)  from  the  urinary  passages 
and  the  bladder  are  generally  present  in  the  urine,  though  in  very  small 
amounts.  According  to  several  investigators  (Leube,  Hopmeister,  Posner), 
normal  human  urine  also  contains  traces  of  albumin. 

Ptomaines  and  leucomaines  or  poisonous  substances  of  an  unknown  kind, 
which  are  often  described  as  alkaloidal  substances,  occur  in  normal  urine 
(PoucHET,  Bouchard,  Adtjcco,  and  others).  Under  pathological  conditions 
the  quantity  of  these  substances  may  be  increased  (Bouchard,  Lepine  and 
GuERiN,  ViLLiERS,  and  others).  Within  the  last  few  years  the  poisonous 
properties  of  urine  have  been  the  subject  of  more  thorough  investigation, 
especially  by  Bouchard.  He  found  that  the  night  urine  is  less  poisonous 
than  the  day  urine,  and  that  the  poisonous  constituents  of  the  day  and  night 
urines  have  not  the  same  action. 

Baumann  and  v.  Udranszkt  have  shown  that  ptomaines  may  occur  in  the 
urine  under  pathological  conditions.  They  demonstrated  the  presence  of  the 
two  ptomaines  discovered  and  first  isolated  by  Brieger — putrescine,  C4H12N2 
(tetramethylendiamin),  and  cadaverin,  CBH14N2  (pentamethylendiamin) — in  the 
urine  of  a  patient  suffering  from  cystinuria  and  catarrh  of  the  bladder. 
Brieger,  v.  Udranszky  and  Baumann  and  Stadthagen  have  shown  that 
not  only  these  but  other  diamins  occur  under  physiological  conditions.  The 
occurrence  in  normal  urine  of  any  "  urine  poison  "  is  denied  by  certain  inves- 
tigators, such  as  Feltz  and  Ritteb  and  Stadthagen.  Tbe  poisonous 
action  of  the  urine,  according  to  them,  is  due  in  great  part  to  the  potassium 
salts. 


THE  URINE.  377 

Many  substances  have  been  observed  in  animal  urine  which  are  not  found 
inhuman  urine.  To  these  belong:  cymirenic  acid,  CioHtNOs,  occurring  in 
dog's  urine  and  which  is  an  oxychinolin  carbonic  acid  ;  urocanic  acid  (Japfe), 
first  found  in  dog's  urine  ;  damaluric  acid  and  damolic  acid  (according  to 
ScHOTTEN,  probably  a  mixture  of  benzoic  acid  wi-th  volatile  fatty  acids), 
obtained  by  the  distillation  of  cow's  urine  ;  and  lastly  the  lithuric  acid,  found 
in  the  urinary  concremeuts  of  certain  animals. 

III.  Inorganic  Constituents  of  Urine. 

Chlorides.  The  chlorine  occurring  in  urine  is  undoubtedly  com- 
bined  with  the  bases  contained  in  this  excretion;  the  chief  part  is 
combined  with  sodium.  In  accordance  with  this,  the  amount  of 
chlorine  in  the  urine  is  generally  expressed  as  NaCl. 

The  amount  of  chlorine  combinations  in  the  urine  is  subject  to 
considerable  variation.  In  general  the  quantity^  for  a  healthy 
grown  person  on  a  mixed  diet  is  10-15  grms.  NaCl  per  24  hours. 
The  quantity  of  common  salt  in  the  urine  depends  chiefly  upon  the 
quantity  of  salt  in  the  food,  with  which  the  elimination  of  chlorine 
increases  and  decreases.  Abundant  drinking  of  water  also  increases 
the  elimination  of  chlorine,  which  is  greater  during  activity  than 
during  rest  (during  night).  Certain  organic  chlorine  combinations, 
such  as  chloroform,  may  increase  the  elimination  of  inorganic  chlo- 
rides by  the  urine  (Zeller,  Mtlius,  Kast). 

In  diarrhoea,  in  quick  formation  of  large  transudations  and 
exudations,  also  in  specially-marked  cases  of  acute  febrile  diseases, 
at  the  time  of  the  crisis,  the  elimination  of  common  salt  is  signifi- 
cantly decreased.  The  elimination  is  abnormally  increased  in  the 
first  days  after  the  crisis  and  during  the  absorption  of  extensive 
exudations.  A  diminished  elimination  of  chlorine  is  found  in 
acute  and  chronic  diseases  of  the  kidneys  accompanied  with  albu- 
minuria. In  chronic  diseases  the  elimination  of  chlorine  in  general 
keeps  pace  with  the  nutritive  condition  of  the  body  and  the  activity 
of  the  secretion  of  the  urine.  As  a  rule  the  chlorine  is  diminished 
in  chronic  diseases. 

The  quantitative  estimation  of  chlorine  in  urine  is  most  simply 
performed  by  titration  with  silver-nitrate  solution.  The  urine 
must  not  contain  either  albumin  (which  if  present  must  be  re- 
moved by  coagulation)  or  iodine  or  bromine  compounds. 

In  the  presence  of  bromides  or  iodides  evaporate  a  measured  quantity  of 
the  urine  to  dryness,  fuse  the  residue  with  saltpetre  and  soda,   dissolve  the 


378  PEYSIOLOOIGAL  CEEMISTBT. 

fused  mass  in  water,  and  remove  the  iodine  or  bromide  by  the  addition  of 
dilute  sulphuric  acid  and  some  nitrite,  and  thoroughly  shake  with  carbon 
disulphide.  The  liquid  thus  obtained  may  now  be  titrated  with  silver  nitrate 
according  to  Volhakd's  method.  The  quantity  of  bromide  or  iodide  is  cal- 
culated as  the  difference  between  the  quantity  of  silver-nitrate  solution  used 
for  the  titration  of  the  solution  of  the  fused  mass  and  the  quantity  used  for 
the  corresponding  volume  of  the  original  urine. 

The  otherwise  beautiful  titration  method  of  Mohr,  according 
to  which  we  titrate  with  silver  nitrate  in  neutral  liquids,  using 
neutral  potassium  chromate  as  an  indicator,  cannot  be  used  directly 
on  the  urine  in  careful  work.  Organic  urinary  constituents  are 
also  precipitated  by  the  silver-salt,  and  the  results  are  therefore 
somewhat  high  for  the  chlorine.  If  we  wish  to  use  this  method, 
the  organic  urinary  constituents  must  first  be  destroyed.  For  this 
purpose  evaporate  to  dryness  5-10  c.c.  of  the  urine,  after  the  addi- 
tion of  1  grm.  of  cLlorine-free  soda  and  1-2  grms.  chlorine-free 
saltpetre,  and  carefully  fuse.  The  mass  is  dissolved  in  water, 
acidified  faintly  with  nitric  acid,  and  then  neutralized  exactly  with 
pure  lime  carbonate.     This  neutral  solution  is  used  for  the  titration. 

The  silver -nitrate  solution  may  be  a  — --  solution.     It  is  often 

•^  10 

made  of  such  a  strength  that  each  c.  c.  corresponds  to  0.006  grm. 

01  or  0.01  grm.  NaOl.  This  last-mentioned  solution  contains 
29.075  grms.  AgNOg  in  1  litre. 

Volhard's  Method.  Instead  of  the  preceding  determination, 
Volhard's  method,  which  can  be  performed  directly  on  the  urine, 
may  be  employed.  The  principle  is  as  follows  :  All  the  chlorine 
from  the  urine  acidified  with  nitric  acid  is  precipitated  by  an  excess 
of  silver  nitrate,  filtered,  and  in  a  measured  part  the  quantity  of 
silver  added  in  excess  is  determined  by  means  of  a  sulphocyanide 
solution.  This. excess  of  silver  is  completely  precipitated  by  the 
sulphocyanide,  and  a  solution  of  some  ferric  salt,  which,  as  is  well 
known,  gives  a  blood-red  reaction  with  the  smallest  quantity  of 
sulphocyanide,  is  used  as  an  indicator. 

We  require  the  following  solutions  for  this  titration  :  1.  A  silver- 
nitrate  solution  which  contains  29.075  grms.  AgNOg  per  litre  and  of 
which  each  c.  c.  corresponds  to  0.01  grm.  NaOl  or  0.00607  grm. 
01 ;  2.  A  saturated  solution  at  the  ordinary  temperature  of 
chlorine-free  iron  alum  or  ferric  sulphate;  3.  Ohlorine-free  nitric 
acid  of  a  specific  gravity  of  1.2  ;  4.  A  potassium  sulphocyanide 
solution  which  contains  8.3  grms.  KONS  per  litre,  and  of  which 

2  c.  c.  corresponds  to  1  c.  c.  of  the  silver-nitrate  solution. 

About  9  grms.  of  potassium  sulphocyanide  are  dissolved  in  water  and 
diluted  to  one  litre.  The  amount  of  KCNS  contained  in  this  solution  is 
determined  by  the  silver-nitrate  solution  in  the  following  way :  Measure 
exactly  10  c.  c.  of  the  silver  solution  and  treat  with  5  c.  c.  of  nitric  acid  and 


THE  URINE.  379 

1-3  c.  c.  of  the  ferric-salt  solution,  and  dilute  with  water  to  about  100  c.  c. 
Now  the  sulphocyauide  solution  is  added  from  a  burette,  constantly  stirring, 
until  a  permanent  faint  red  coloration  of  the  liquid  takes  place.  The  amount 
of  sulphocyauide  found  in  the  solution  by  this  means  indicates  how  much  it 
must  be  diluted  to  be  of  the  proper  strength.  Titrate  once  more  with  10  c.  c. 
AgNOa  solution  and  correct  the  sulphocyanide  solution  by  the"  careful  addition 
of  water  until  20  c.  c.  exactly  correspond  to  10  c.  c.  of  the  silver  solution. 

The  determination  of  the  chlorine  in  the  urine  is  performed  by 
this  method  in  the  following  way  :  Exactly  10  c.  c.  of  the  urine 
are  placed  in  a  flask  which  has  a  mark  corresponding  to  100  c.  c.  ; 
5  c.  c.  nitric  acid  are  added  ;  dilute  with  about  50  c.  c.  water,  and 
tlien  allow  exactly  20  c.  c.  of  the  silver-nitrate  solution  to  flow  in. 
Close  the  flask  with  the  thumb  and  shake  well,  slide  off  the  thumb 
and  wash  it  with  distilled  water  into  the  flask,  and  fill  the  flask  to 
the  100-c.  c.  mark  with  distilled  water.  Close  again  with  tlie 
thumb,  carefully  mix  by  shaking,  and  filter  through  a  dry  filter. 
Measure  off  50  c.  c.  of  the  filtrate  by  means  of  a  pipette,  add  3  c.  c. 
ferric-salt  solution,  and  allow  the  sulphocyanide  solution  to  flow  in 
until  the  liquid  above  the  precipitate  has  a  permanent  red  color. 
The  calculation  is  very  simple.  For  example,  if  4.6  c.  c.  of  the 
sulphocyanide  solution  were  necessary  to  produce  the  final  reaction, 
then  for  100  c.  c.  of  the  filtrate  (  =  10  c.  c.  urine)  9.2  c.  c.  of  this 
solution  are  necessary.  9.2  c.  c.  of  the  sulphocyanide  solution 
corresponds  to  4.6  c.  c.  of  the  silver  solution,  and  since  20  —  4.6 
=  15.4  c.  c.  of  the  silver  solution  were  necessary  to  completely 
precipitate  the  chlorides  in  10  c.  c.  of  the  urine,  then  10  c,  c.  con- 
tain 0.154  grni.  NaCl.  The  amount  of  sodium  chloride  in  the 
urine  is  therefore  1.54^  or  15.4  Voo.  If  we  always  use  10  c.  c.  for  the 
determination,  and  always  20  c.  c.  AgNOj ,  and  dilute  with  water  to 
100  c.  c,  we  find  the  amount  of  NaCl  in  1000  parts  of  the  urine  by 
subtracting  the  number  of  c.  c.  of  sulphocyanide  (E)  i-equired  with 
50  c.  c.  of  the  filtrate  from  20.  Tiie  quantity  of  NaCl  p.  m.  is 
therefore  under  these  circumstances  =  20  —  R,  and  the  percentage 

of  NaCl  =  ^^^. 

The  approximate  estimation  of  chlorine  in  the  urine  (which 
must  be  free  from  albumin)  is  made  by  strongly  acidifying  with 
nitric  acid  and  then  adding  to  it,  drop  by  drop,  a  concentrated 
silver-nitrate  solution  (1 :  8).  In  a  normal  amount  of  chlorides  the 
drop  sinks  to  the  bottom  as  a  rather  compact  cheesy  lump.  In 
diminished  amounts  of  chlorides  the  precipitate  is  less  compact  and 
coherent,  and  in  the  presence  of  very  little  chlorine  a  fine  white 
precipitate  or  only  a  cloudiness  or  opalescence  is  obtained. 

Phosphates.  Phosphoric  acid  occurs  in  acid  urines  partly  as 
double-,  MHgPOo  and  partly  as  simple-acid,  MjHPOi,  phosphates. 


360  PHYSIOLOOIGAL   CEEMISTBT. 

both  of  which  are  found  in  acid  urines  at  the  same  time.  Ott 
found  that  on  an  average  60^  of  the  total  phosphoric  acid  was 
double-  and  40^  was  simple-acid  phosphate.  The  total  quantity  of 
phosphoric  acid  is  very  variable  and  depends  on  the  kind  and  the 
quantity  of  food.  The  average  amount  of  P2O5  is  in  round  num- 
bers 2.5  grms.,  with  a  variation  of  1-5  grms.,  per  34  hours.  The 
phosphoric  acid  of  the  urine  originates  to  a  small  extent  from  the 
burning  of  organic  compounds,  nuclein,  protagon  and  lecithin, 
within  the  organism.  The  greater  part  originates  from  the  phos- 
phates of  the  food,  and  the  quantity  of  eliminated  phosphoric  acid 
is  greater  when  the  food  is  rich  in  alkali  phosphates  in  proportion 
to  the  quantity  of  lime  and  magnesia  phosphates.  If  the  food  con- 
tains much  lime  and  magnesia,  large  amounts  of  earthy  phosphates 
are  eliminated  by  the  excrements;  and  even  though  the  food  con- 
tains considerable  amounts  of  phosphoric  acid  in  these  cases,  the 
quantity  of  phosphoric  acid  in  the  urine  is  small.  Such  a  condition 
is  found  in  the  herbivora,  whose  urine  is  habitually  poor  in  phos- 
phates. The  extent  of  the  elimination  of  phosphoric  acid  by  the 
urine  depends  not  only  upon  the  total  quantity  of  phosphoric  acid 
in  the  food,  but  also  upon  the  relative  amounts  of  alkaline  earths 
and  the  alkali  salts  in  the  food. 

From  the  transformation  of  tissues  rich  in  proteid  or  of  phos- 
phorized  nerve-substance  in  the  body  we  might  perhaps  expect  an 
equal  relation  between  the  nitrogen  and  the  phosphoric  acid  in  the 
urine.  Many  investigations  have  been  made  upon  this  subject  by 
Zuelzer,  Strijbin'g,  and  Edlefsseist;  but  as  all  the  conditions 
which  affect  the  elimination  of  phosphoric  acid  are  not  yet  suffi- 
ciently known,  it  is  difficult  to  draw  any  definite  conclusions  from 
the  observations  thus  far  made. 

Little  is  known  in  regard  to  the  elimination  of  phosphoric  acid 
in  disease.  In  febrile  diseases  the  amount  of  phosphoric  acid  is 
considerably  decreased  as  compared  with  the  urea  (Zuelzer).  In 
diseases  of  the  kidneys  the  activity  of  these  organs  in  eliminating 
the  phosphates  is  considerably  diminished  (Fleischer).  In  men- 
ingitis, on  the  contrary,  a  marked  increase  in  the  phosphates  is 
observed  in  the  urine.  Teissier  has  described  a  special  form  of 
polyuria,  in  which  abundant  quantities  of  earthy  phosphates, 
10-20-30  grms.  per  24  hours,  were  eliminated.     This  polyuria  was 


THE  URINE.  381 

called  PHOSPHATE  DIABETES  by  Teissier.  The  statements  in 
regard  to  the  amount  of  phosphate  iu  the  urine  in  rachitis  and  in 
osteomalacia  are  somewhat  contradictory.  A  diminished  elimina- 
tion of  phosphoric  acid  has  been  observed  by  Stokyis  in  arthritis. 

Quantitative  estimation  of  phospJwric  acid  in  the  urine.  This 
estimation  is  most  simply  performed  by  titrating  with  a  solution  of 
uranium  acetate.  The  principle  of  the  titration  is  as  follows  :  A 
warm  solution  of  phosphates  containing  free  acetic  acid  gives  a 
whitish-yellow  precipitate  of  uranium  phosphate  with  a  solution  of 
a  uranium  salt.  This  precipitate  is  insoluble  in  acetic  acid,  but 
dissolves  in  mineral  acids,  and  on  this  account  we  always  add  in 
titrating  a  certain  quantity  of  sodium  acetate  solution.  Potassium 
ferrocyanide  is  used  as  the  indicator,  which  does  not  act  on  the 
uranium-phosphate  precipitate,  but  gives  a  reddish-brown  precipi- 
tate or  coloration  in  the  presence  of  the  smallest  amount  of  soluble 
uranium  salt.  The  solutions  necessary  for  the  titration  are  :  1.  A 
solution  of  a  uranium  salt  of  which  each  c.  c.  corresponds  to  0.005 
grm.  P2O5  and  which  contains  20.3  grms.  uranium  oxide  per  litre. 
20  c.  c.  of  this  solution  corresponds  to  0.100  grm.  P2O5.  2.  A  solu- 
tion of  sodium  acetate  ;  3.  A  freshly-prepared  solution  of  potas- 
sium ferrocyanide. 

The  uranium  solution  is  prepared  from  uranium  nitrate  or  acetate.  Dis- 
solve about  35  trrms.  uranium  acetate  in  water,  add  some  acetic  acid  to  facilitate 
solution,  and  dilute  to  one  litre.  The  strength  of  this  sohition  is  determined 
by  titratina:  with  a  solution  of  sodium  phosphate  of  known  strength  (10.085 
grms.  crj-slallized  salt  in  1  litie.  which  corresponds  to  0.100  grm.  P0O5  in 
50  c.  c).  Proceed  in  the  same  way  as  in  the  titration  of  the  urine  (see  below) 
and  correct  the  solution  by  diluting  with  water,  and  titrate  again  until  20  c  c. 
of  the  uranium  solution  correspond  exactly  to  50  c.  c.  of  the  above  phosphate 
solution. 

The  sodium-acetate  solution  should  contain  10  grms.  sodium  acetate  and  10 
grms.  cone,  acetic  acid  in  100  c.  c.  For  each  titration  5  c.  c.  of  this  solution  is 
used  with  50  c.  c.  of  the  urine. 

In  performing  the  titration,  mix  50  c.  c.  of  filtered  urine  in  a 
beaker  with  5  c.  c.  of  the  sodium  acetate,  cover  the  beaker  with  a 
watch-glass,  and  warm  over  the  water-bath.  Then  allow  the  ura- 
nium solution  to  flow  in  from  a  burette,  and,  when  the  precipitate 
does  not  seem  to  increase,  place  a  drop  of  the  mixture  on  a  porce- 
lain plate  with  a  drop  of  the  potassium-ferrocyanide  solution.  If 
the  amount  of  uranium  solution  employed  is  not  sufficient,  the  color 
remains  pale  yellow  and  more  uranium  solution  must  be  added; 
but  as  soon  as  the  slightest  excess  of  uranium  has  been  used,  the 
color  becomes  faint  reddish  brown.  When  this  point  has  been 
obtained,  warm  the  solution  again  and  add  another  drop.  If  the 
color  remains  of  the  same  intensity,  the  titration  is  ended  ;  but  if 


382  PHYSIOLOGICAL  CHEWISTRT. 

the  color  varies,  add  more  uranium  solution,  drop  by  drop,  until  a 
permanent  coloration  is  obtained  after  warming,  and  now  repeat 
the  test  with  another  50  c.  c.  of  the  urine.  The  calculation  is  so 
simple  that  it  is  unnecessary  to  give  an  example. 

In  the  above  manner  we  determine  the  total  quantity  of  phos- 
phoric acid  in  the  urine.  If  we  wish  to  know  the  phosphoric  acid 
combined  with  alkaline  earths  or  with  alkalies,  we  first  determine 
the  total  phosphoric  acid  in  a  portion  of  the  urine  and  then  remove 
the  earthy  phosphates  in  another  portion  by  ammonia.  The  precip- 
itate is  collected  on  a  filter,  washed,  transferred  in  a  beaker  with 
water,  treated  w^th  acetic  acid,  and  dissolved  by  warming.  This 
solution  is  now  diluted  to  50  c.  c.  with  water,  and  5  c.  c.  sodium- 
acetate  solution  added,  and  titrated  wath  uranium  solution.  The 
difference  between  the  two  determinations  gives  the  quantity  of 
phosphoric  acid  combined  with  the  alkalies. 

Sulphates.  The  sulphuric  acid  of  the  urine  originates  only  to  a 
very  small  extent  from  the  sulphates  of  the  food.  A  dispropor- 
tionally  greater  part  is  formed  by  the  burning  of  the  proteids  con- 
taining sulphur  within  the  body,  and  it  is  chiefly  this  formation  of 
sulphuric  acid  from  the  proteids  which  gives  rise  to  the  previously- 
mentioned  excess  of  acids  over  the  bases  in  the  urine.  The  quan- 
tity of  sulphuric  a<3id  eliminated  by  the  urine  amounts  to  about  2.5 
grms.  HjSO,  per  twenty-four  hours.  As  the  sulphuric  acid  chiefly 
originates  from  the  proteids,  it  follows  that  the  elimination  of 
sulphuric  acid  and  the  elimination  of  nitrogen  are  nearly  parallel, 
and  the  relationship  N  :  H^SO^  is  about  5  :  1.  Sulphuric  acid 
occurs  in  the  urine  partly  preformed  (sulphate-sulphuric  acid)  and 
paytly  as  ethereal  sulphuric  acid. 

The  quantity  of  total  sulpliuric  acid  is  determined  in  the  fol- 
lowiag  way,  but  at  the  same  time  the  precautions  described  in 
other  works  must  be  observed:  100  c.  c.  of  filtered  urine  are 
treated  with  5  c.  c.  concentrated  hydrochloric  acid  and  boiled  for 
fifteen  minutes.  While  boiling  precipitate  with  2  c.  c.  of  a  satu- 
rated BaClj  solution  and  warm  for  a  little  while  until  the  barium 
sulphate  has  completely  settled.  The  precipitate  must  then  be 
washed  with  water  or  with  alcohol  and  ether  (to  remove  resinous 
substances)  and  then  treated  according  to  the  usual  method. 

The  .separate  determination  of  the  sulphate-sulphuric  acid  and 
the  ethereal  sulphuric  acid  may  be  done,  according  to  BAUiiANN's 
method,  by  first  precipitating  the  sulphate-sulphuric  acid  from  the 
urine  acidified  with  acetic  acid,  by  BaCl^ ,  and  then  decomposing 
the  ethereal  sulphuric  acid  by  boiling  after  the  addition  of  hydro- 


THE  XmiNE.  383 

chloric  acid,  and  then  determining  the  sulphuric  acid  set  free  as 
barium  sulphate.  A  still  better  method  is  the  following  suggested 
by  Salkowski  : 

200  c.  c.  of  urine  are  precipitated  by  an  equal  volume  of  a 
barium  solution  which  consists  of  2  vols,  barium  hydrate  and  1  vol. 
barium-chloride  solution,  both  saturated  at  the  ordinary  temper- 
ature. Filter  through  a  dry  filter,  measure  off  100  c.  c.  of  the 
filtrate  which  contains  only  the  ethereal  sulphuric  acid,  treat  with 
10  c.  c.  hydrochloric  acid  of  a  specific  gravity  1.12,  boil  for  fifteen 
minutes,  and  then  warm  on  the  water-bath  until  the  precipitate 
has  completely  settled  and  the  supernatant  liquid  is  entirely  clear. 
"Wash  with  warm  water  and  with  alcohol  and  ether  and  proceed 
according  to  the  generally-prescribed  method.  The  difference 
between  the  ethereal  sulphuric  acid  found  and  the  total  quantity 
of  sulphuric  acid  as  determined  in  a  special  portion  of  urine  is 
considered  as  the  quantity  of  sulphate-sulphuric  acid. 

Nitrates  occur  in  small  quantities  in  human  urine  (Schojtbein),  and  they 
probably  originate  from  the  drinklug-water  and  the  food.  According  to 
Weyi,  and  Citron,  the  quantity  of  nitrates  is  smallest  with  a  meat  diet  and 
greatest  with  vegetable  food.  The  average  amount  is  about  43.5  milligrammes 
per  litre. 

Potassium  and  Sodium.  The  quantity  of  these  bodies  eliminated 
by  the  urine  by  a  healthy  full-grown  person  on  a  mixed  diet  is, 
according  to  Salkowski,  3-4  grms.  K.^O  and  5-7.5  grms.  Xa^O. 
The  proportion  of  K  to  Xa  is  ordinarily  as  3:5.  The  amount 
depends  above  all  upon  the  food.  In  starvation  the  urine  may 
become  richer  in  potassium  than  in  sodium,  which  results  from 
the  lack  of  common  salt  and  the  destruction  of  tissue  rich  in  po- 
tassium. The  quantity  of  potassium  may  be  relatively  increased 
during  fever,  while  after  the  crisis  the  reverse  is  the  case. 

The  quantitative  estimation  of  these  bodies  is  performed  by  the 
gravimetric  methods  as  described  in  anah-tical  works. 

Ammonia.  Some  ammonia  is  habitually  found  in  human  urine 
and  in  that  of  carnivora.  This  ammonia  may  represent,  as  above 
stated  (page  338),  on  the  formation  of  urea  from  ammonia,  the 
small  amount  of  ammonia  which,  because  of  the  excess  of  acids 
formed  by  the  combustion,  as  compared  to  the  fixed  alkalies,  is 
united  with  such  acids  and  in  this  way  excluded  from  the  synthesis 
to  urea.  These  views  are  confirmed  by  the  observations  of  Co- 
RANDA,  who  found  that  the  elimination  of  ammonia  was  smaller  on 
a  vegetable  diet  and  larger  on  a  rich  meat  diet  than  when  on  a 


384  PHYSIOLOOIGAL   CEEMI8TRT. 

mixed  diet.  On  a  mixed  diet  tlie  average  amount  of  ammonia 
eliminated  by  the  urine  is  about  0.7  grm.  NH,  per  twenty-four 
hours  (NeubAuer). 

The  quantity  of  ammonia  in  human  urine  and  that  of  carnivora 
is  increased  by  the  introduction  of  mineral  salts  and  also  in  diseases 
in  which  an  increased  formation  of  acid  takes  place  due  to  an  in- 
creased metabolism  of  proteids.  This  is  the  case  in  fevers  and 
diabetes.  In  the  last-mentioned  disease  an  organic  acid,  y5-oxybu- 
tyric  acid,  is  produced  (Minkowski,  Ktjlz,  Stadelmann)  which 
passes  into  the  urine  combined  with  ammonia.  In  diseases  of  the 
liver,  as  in  acute  yellow  atrophy  and  interstitial  hepatitis  (Haller- 
VORDEE",  Stadelmann),  the  formation  of  urea  may  decrease  and 
the  elimination  of  ammonia  increase.     In  these  cases  the  propor- 

+  .  . 

tion  of  NH3  :  Ur,  which,  according  to  STADELMAii^K,  is  normally 

3.8  :  100,  may  be  changed.     The  same  may  also  be  observed  in 

acute   phosphorus-poisoning.     In  such  a  case  K.  Morner  found 

the  relation  5.3  :  100. 

The  detection  and  quantitative  estimation  of  ammonia  is  per- 
formed according  to  the  method  suggested  by  Schlosing.  The 
principle  of  this  method  is  that  the  ammonia  from  a  measured 
amount  of  urine  is  set  free  by  lime-water  in  a  closed  vessel  and 

N 
absorbed  by  a  measured  amount  of  tt.  sulphuric  acid.     After  the 

absorption  of  the  ammonia  the  quantity  is  determined  by  titrating 

N  .  .  . 

the  remaining  free  sulphuric  acid  with  a  ^  caustic  alkali.      This 

method  gives  low  results,  and  in  exact  work  we  must,  proceed  as 
suggested  by  Bohland  (Pflijger's  Archiv,  vol  43,  page  33).  Other 
methods  have  been  suggested  by  Schmiedeberg  and  by  Latschen"- 

BERGER. 

Calcium  and  magnesium  occur  in  the  urine  for  the  most  part  as 
phosphates.  The  quantity  of  earthy  phosphates  eliminated  daily 
is  somewhat  more  than  1  gr.,  and  of  this  amount  |  is  magnesium 
and  1  calcium  phosphate.  In  acid  urines  the  simple-  as  well  as  the 
double-acid  earthy  phosphates  are  found,  and  the  solubility  of  the 
first,  among  which  the  calcium-salt,  CaHPOi,  is  especially  insol- 
uble, is  particularly  augmented  by  the  psesence  of  double-acid  al- 
kali phosphate  and  sodium  chloride  in  the  urine  (Ott).    The  quan- 


THE  UEINE.  385 

tity  of  alkaline  earths  in  the  urine  depends  on  the  composition  of 
the  food.  Nothing  is  known  with  positiveness  in  regard  to  the  con- 
stant and  regular  change  in  the  elimination  of  these  substances  in 
disease. 
■  The  quantity  of  calcium  and  magnesium  is  determined  accord- 
ing to  the  ordinary  well-known  methods. 

Iron  occurs  in  the  urine  only  In  small  amounts,  and,  as  it  seems,  not  as  a 
salt,  but  as  an  organic  combination— part  perhaps  as  pigment  or  chromogen 
(KoNKEL,  Giacosa)  and  part  in  other  forms.  According  to  Magnier,  the 
quantity  of  iron  in  1  litre  of  urine  is  3-11  milligrms.  According  to  Gottlieb, 
the  elimination  of  iron  by  the  healthy  human  urine  amounts  to  2.59  milligrms. 
per  day.  Iron-salts  introduced  into  the  intestine  do  not  pass  into  the  urine  at 
all,  or  only  in  very  small  amounts.  The  quantity  of  silicic  acid,  according  to 
the  ordinary  statements,  amounts  to  about  0.03  p.  m.  Traces  of  hydrogen  per- 
oxide also  occur  in  the  urine. 

The  gases  of  the  urine  are  carbon  dioxide,  nitrogen,  and  traces 
of  oxygen.  The  quantity  of  nitrogen  is  not  quite  1  vol.  per  cent. 
The  carbon  dioxide  varies  considerably.  In  acid  urines  it  is  hardly 
one  half  as  great  as  in  neutral  or  alkaline  urines. 


IV.  The  Amount  and  Quantitative  Composition  of  Urine. 

A  direct  participation  of  the  kidney  substance  in  the  formation 
of  the  urinary  constituents  is  proved  at  least  for  hippuric  acid.  It 
is  hardly  to  be  doubted  that  the  kidneys  as  well  as  the  tissues  gen- 
erally have  a  certain  part  to  play  in  the  formation  of  other  urinary 
constituents,  but  their  chief  task  consists  in  separating  and  remov- 
ing urinary  constituents  dissolved  in  the  blood  which  have  been 
taken  up  by  it  from  other  organs  and  tissues. 

It  has  been  shown  by  the  experiments  of  numerous  investiga- 
tors, Heidenhain,  v.  Wittich,  Nussbaum,  Neisser,  Ustimo- 
wiTSCH,  J.  MuNK,  and  others,  that  the  elimination  of  water  and 
the  remaining  urinary  constituents  is  not  alone  produced  by  simple 
diffusion  and  filtration.  It  is  generally  conceded  that  the  processes 
of  urinary  secretion  depend  essentially  upon  a  specific  activity  of 
the  cells  of  the  epithelium  of  the  urinary  passages,  besides  which 
also  processes  of  filtration  and  diffusion  take  part.  The  process  of 
the  secretion  of  urine  in  man  and  the  higher  animals  is  generally 
considered  to  proceed  chiefly  as  follows:  The  water  together  with 


386  PHYSIOLOGICAL   CHEMISTRT. 

a  small  amount  of  the  salts  passes  tlirougli  the  glomeruli  Mal- 
pighii,  while  the  chief  part  of  the  solids  is  secreted  by  the  epithe- 
lium of  the  urinary  passages.  A  secretion  of  solids  without  a  simul- 
taneous secretion  of  water  is  not  possible,  and  therefore  a  part  of  - 
the  water  must  be  secreted  by  the  epithelium-cells  of  the  urinary 
passages.  The  passage  of  the  chief  part  of  the  water  through  the 
glomeruli  is  rather  generally  considered  as  a  filtration  due  to  blood- 
pressure.  According  to  Heidekhain",  the  thin  cell-layers  of  the 
glomeruli  have  a  secretory  action. 

The  amount  and  the  composition  of  urine  is  liable  to  great 
variation.  Those  circumstances  which  under  physiological  condi- 
tions exercise  a  great  influence  are  the  following:  the  blood-pres- 
sure, and  the  rapidity  of  the  blood-current  in  the  glomeruli;  the 
quantity  of  urinary  constituents,  especially  water  in  the  blood; 
and  lastly,  the  condition  of  the  secretory  glandular  elements. 
Above  all,  the  amount  and  concentration  of  the  urine  depend  on 
the  elimination  of  water.  That  this  last  may  vary  with  the  amount 
of  water  in  the  blood,  with  changed  blood-pressure,  and  with  cir- 
culatory conditions  is  evident;  but  under  ordinary  circumstances  the 
amount  of  water  eliminated  by  the  kidneys  depends  essentially 
upon  the  quantity  of  water  which  is  brought  to  them  by  the  blood, 
■or  which  leaves  the  body  by  other  exits.  The  elimination  of  urine 
is  increased  by  abundant  drinking  or  if  the  amount  of  water  re- 
moved in  other  ways  is  lessened;  but  it  is  decreased  by  a  dimin- 
ished introduction  of  water,  or  by  a  greater  loss  of  water  in  other 
ways.  Ordinarily  in  man  just  as  much  water  is  eliminated  by  the 
kidneys  as  by  the  skin,  lungs,  and  intestines  together.  At  lower 
temperatures  and  in  moist  air,  since  under  these  conditions  the 
elimination  of  water  by  the  skin  is  diminished,  the  elimination  of 
urine  may  be  considerably  increased.  Diminished  introduction  .of 
water  or  diminished  secretion  of  water — as  in  violent  diarrhoea,  vio- 
lent vomiting,  or  abundant  perspiration — greatly  diminishes  the 
elimination  of  urine.  For  example,  the  urine  may  sink  as  low  as 
500-400  c.  c.  per  day  in  intense  summer-heat,  while  after  copious 
draughts  of  water  the  elimination  of  3000  c.  c.  of  urine  has  been 
observed  during  the  same  time.  The  average  quantity  of  urine 
secreted  in  the  course  of  24  hours  for  healthy  grown  men  is  1500 
c.  c,  and   for  women  1300  c.  c.    The  minimum  secretion  occurs 


TEE  URINE.  387 

during  the  night  between  2-4  o'clock;  the  maximum,  in  the  first 
hours  after  awakening  and  from  1-2  hours  after  a  meah 

The  quantity  of  solids  secreted  in  the  course  of  24  hours  is 
rather  constant  even  though  the  quantity  of  urine  may  vary,  and 
it  is  more  constant  when  the  manner  of  living  is  regular.  There- 
fore the  percentage  of  solids  in  the  urine  is  naturally  in  an  inverse 
proportion  to  the  quantity  of  urine.  The  average  quantity  of 
solids  per  24  hours  is  calculated  as  60  grms.  The  quantity  may  be 
calculated  with  approximate  accuracy  by  means  of  the  specific 
gravity,  if  the  second  and  third  decimals  of  the  specific  gravity  be 
multiplied  by  Haser's  coefficient  2.33.  The  product  gives  the 
amount  of  solids  in  1000  c.c.  of  urine,  and  if  the  quantity  of 
urine  eliminated  in  the  24  hours  be  measured,  the  quantity  of 
solids  in  the  24  hours  may  be  easily  calculated.  For  example, 
1050  c.c.  of  urine  of  a  sp.  gr.  1.021  was  eliminated  in  the  24  hours; 
therefore  the   quantity  of  solids  eliminated  is  31  X  2.33  =  48.9, 

48.9  X  1050 
and  -- — -  =  51.35  grms.     The  urine  in  this  case  contained 

48.9  p.  m.  solids  and  51.35  grms.  in  the  daily  secretion. 

Those  bodies  which,  under  physiological  conditions,  affect  the 
density  of  the  urine  are  common  salt  and  urea.  The  specific  gravity 
of  the  first  is  2.15  and  the  last  only  1.32,  so  it  is  easy  to  understand, 
when  the  relative  proportion  of  these  two  bodies  essentially  de- 
viates from  the  normal,  why  the  above,  calculation  from  the  specific 
gravity  is  not  exact.  The  same  is  the  case  when  a  urine  poor  in 
a  normal  constituent  contains  large  amounts  of  foreign  bodies,  such 
as  albumin  or  sugar. 

As  above  stated,  the  percentage  of  solids  in  the  urine  generally 
decreases  Avith  a  greater  elimination,  and  an  abundant  secretion 
{polyuria)  has  therefore,  as  a  rule,  a  lower  specific  gravity.  An 
important  exception  to  this  rule  is  observed  in  urine  containing 
sugar  {diabetes  meUihts),  in  which  there  is  a  very  abundant  secre- 
tion of  a  very  high  specific  gravity  due  to  the  sugar.  In  cases 
where  very  little  urine  is  secreted  [oliguria),  as  when  the  perspira- 
tion is  profuse,  in  diarrhoia,  and  in  fevers,  the  specific  gravity  is  as. 
a  rule  high,  the  percentage  of  solids  high,  and  the  color  dark. 
Sometimes,  as,  for  example,  in  certain  cases  of  albuminuria,  the 


388  PHYSIOLOGICAL   CHEMISTBT. 

reverse  of  the  above  may  be  observed  even  though  the  urine  has  a 
low  specific  gravity,  a  pale  color,  and  is  poor  in  solids. 

It  is  difl&cult  to  give  a  tabular  view  of  the  composition  of  urine, 
on  account  of  its  variation.  For  certain  purposes  the  following 
table  may  be  of  some  value,  but  it  must  not  be  overlooked  that  the 
results  are  not  given  for  1000  parts  of  urine,  but  only  approximate 
figures  for  the  amounts  of  the  most  important  constituents  which 
are  eliminated  in  the  course  of  24  hours  in  a  quantity  of  1500  c.c. 

Daily  amount  of  solids  =  60  grms. 


Organic  constituents =  35  grms. 

Urea 30       ' 

Uric  acid 0.7 

Creatinin 1.0 

Hippuric  acid 0.7 

Remaining  organic  bodies  2.6 


Inorganic  constituents. .  =  25    grms. 

Sodium  chloride  (NaCl).  15.0  " 

Sulphuric  acid  (H2SO4).     2.5  " 

Phosphoric  acid  (P^Os)..     2.5  " 

Potash  (K2O) 3.3  " 

Ammonia  (NH3) 0.7  " 

Magnesia  (MgO) 0.5  " 

Lime(CaO) 0.3  " 

Remaining  inorg.  bodies    0.2  " 


Urine  contains  on  an  average  40  p.  m.  solids.  The  amount  of 
urea  is  about  20  p.  m.  and  common  salt  about  10  p.  m. 

V.  Casual  Urinary  Constituents. 

The  casual  appearance  in  the  urine  of  medicines  or  of  urinary 
constituents  resulting  from  the  introduction  of  foreign  substances 
into  the  organism  is  of  practical  importance,  because  such  constit- 
uents may  interfere  in  certain  urinary  investigations  and  also 
because  they  afford  a  good  means  of  determining  whether  certain 
substances  have  been  introduced  into  the  organism  or  not.  From 
this  point  of  view  a  few  of  these  bodies  will  be  spoken  of  in  a 
following  section  (on  the  pathological  urinary  constituents).  The 
presence  of  these  foreign  bodies  in  the  urine  is  of  special  interest 
in  those  cases  in  which  they  serve  to  elucidate  the  chemical  trans- 
formations certain  substances  undergo  within  the  body.  As  inor- 
ganic substances  generally  leave  the  body  unchanged,  they  are  of 
very  little  interest  from  this  standpoint,  but  the  changes  which 
certain  organic  substances  undergo  may  be  studied  by  this  means 
so  far  as  these  transformations  are  shown  by  the  urine. 

The  bodies  belonging  to  the  fatty  series,  though  not  without 
exceptions,  fall  mostly  into  a  combustion  leading  towards  the  end- 


THE  URINE.  389 

products  of  the  exchange  of  material;  still,  often  a  smaller  or 
greater  part  of  the  body  iu  question  withdraws  itself  from  oxidation 
and  appears  unchanged  in  the  urine.  A  part  of  the  organic  acids, 
which  are  otherwise  burnt  into  water  and  carbonates  and  render 
the  urine  neutral  or  alkaline  act  in  this  way.  The  volatile  fatty 
acids  poor  in  carbon  are  less  easily  burnt  than  those  rich  in  carbon, 
and  they  therefore  pass  in  large  amounts  unchanged  into  the  urine. 
This  is  especially  true  of  formic  and  acetic  acids  (Schotten", 
Grehant  and  Quinquand).  Oxalic  acid  passes  completely  or 
almost  completely  unchanged  into  the  urine  (Gaglio). 

The  acid  amides  appear  not  to  be  changed  in  the  body 
(ScHULTZEN"  and  Nencki).  A  small  part  of  the  amido-acids  seem 
indeed  to  be  eliminated  unchanged,  but  otherwise  they  are,  as  stated 
above  (page  338)  for  leucin,  glycocoU  and  aspartic  acid,  decomposed 
within  the  body,  and  they  may  therefore  cause  an  increased  elimi- 
nation of  urea.  Sarcosin  (methylglycocoU),  NH(CH3).CH2.COOH, 
also  perhaps  passes  in  small  part  into  the  corresponding  uramido- 
acid,  methylliydantoinic  acid,  NH2.CO.]Sr(CH3).CH2.COOH.  Also 
taurin,  amido-ethylsulphonic  acid,  which  acts  somewhat  differently 
in  different  animals  (Salkowski),  passes  in  human  beings,  at  least 
in  part,  into  the  corresponding  uramido-acid,  taurocarhaminic  acid, 
NH2.CO.NH.C2H4.SO2  .OH.  A  part  of  the  taurin  appears  as  such 
in  the  urine.  In  rabbits,  when  taurin  is  introduced  into  the 
stomach,  nearly  all  its  sulphur  appears  in  the  urine  as  sulphuric  and 
sulphurous  acids.  After  subcutaneous  injection  the  taurin  appears 
again  in  great  part  unchanged  in  the  urine. 

Creatin  passes,  at  least  in  part,  into  creatinin.  A  part  may  perhaps 
appear  as  urea  (see  page  357).     Hijfoxanthin  passes  into  uric  acid. 

A  coupling  tvith  glycocoU  may  also  occur.  Furfurol  or  the 
anhydride  of  pyromucic  acid,  C5H4O2,  passes  to  a  great  extent 
coupled  with  glycocoU  as  pyromucuric  acid,  C7H7N4O,  into  the  urine 
of  rabbits  and  dogs  and  to  a  less  extent  as  furfuracrylic  acid 
coupled  with  glycocoU  as  furfur acryhiric  acid,  CgHgNtO  (Jaffe 
and  Cohn).  In  birds  (hens)  this  condition  is  different.  In  these 
animals  furfurol  gives  pyromucic  acid  and  a  coupled  acid, 
pyromucinornithuric  acid,  C15H16N2O6 ,  which  decomposes  on  warm- 
ing  with  concentrated  hydrochloric  acid  into  pyromucic  acid  and 
ornithin,  C6H12N2O2  (Jaffe  and  Cohn). 


390  PHTSIOLOQICAL   CHEMISTRY. 

Couijling  with  glycuronic  acid  occurs  in  certain  substituted 
alcohols,  aldehydes  and  ketones  (?),  which  probably  first  pass  over 
into  alcohol  (Sundvik).  Chloral  hydrate,  C2CI3OH+H2O,  passes, 
after  it  has  been  converted  into  trichlorethyl-alcohol  by  a  reduc- 
tion, into  a  Isevo-gyrate  reducible  acid,  urocJiloralic  acid  or 
trichlorethyl-glycuronic  acid,  CgClsHg.CeHjOy  (Musculus  and 
y.  Merikg).  TricJilorhutyl-alcolwl  and  iutyl-chloral  hydrate  also 
pass  into  trichlorbutyl- glycuronic  acid.  Tertiary  amyl-  and  butyl- 
alcohol  also  undergo  (in  rabbits  but  not  in  man)  a  coupling  with 
glycuronic  acid.  In  animals  which  have  starved  until  the  glycogen 
has  disappeared  from  the  muscles  and  liver  and  which  are  given 
chloral  hydrate  or  dimethyl  carbinol,  coupled  glycuronic  acidg^ 
appear  in  the  urine  (Thieefelder).  On  account  of  these  facts  the 
albuminous  bodies  are  considered  the  origin  of  the  glycuronic 
acid.  It  may  perhaps  originate  from  such  bodies  as  the  proteids 
which  are  found  widely  diffused  in  the  body  and  from  which 
carbohydrates  or  near-related  acids  may  be  split. 

The  aromatic  combinations  pass  as  a  rule,  so  far  as  we  know, 
into  the  urine  after  a  previous  partial  oxidation  or  after  a  synthesis 
with  other  bodies.  The  question  whether  the  benzol  ring  ia 
destroyed  in  the  body  is  still  undecided,  but  at  least  in  certain 
cases  such  a  destruction  is  very  probable. 

The  fact  that  benzol  may  be  oxidized  outside  of  the  body  into 
carbon  dioxide,  oxalic  acid,  and  volatile  fatty  acids  has  been  known 
for  a  long  time,  and  we  may  refer  the  reader  to  the  investigations 
of  Drechsel,  mentioned  in  the  first  chapter,  in  which  this 
experimenter  obtained,  by  the  electrolysis  of  phenol,  normal  caproic 
acid  and  afterward  substances  in  which  the  amount  of  carbon 
decreased  constantly  until  he  obtained  the  end-products  of  the 
exchange  of  material.  As  in  these  experiments  a  splitting  of  the 
benzol  ring  must  take  place  before  the  formation  of  the  body  of 
the  fatty  series,  also  when  aromatic  bodies  are  burnt  in  the  animal 
body,  we  must  admit  that  first  a  rupture  of  the  benzol  ring  takes 
place  with  the  formation  of  fatty  bodies.  If  this  does  not  take 
place,  then  the  benzol  nucleus  is  eliminated  with  the  urine  as  an 
aromatic  combination  of  one  kind  or  another.  As  the  diflficultly- 
burnt  benzol  nucleus  can  protect  from  destruction  a  substance 
belonging  to  the  fatty  series  and  coupled  with  it,  which  is  the  case 


THE   URINE.  391 

with  the  glycocoll  of  hi])puric  acid,  it  seems  also  that  the  aromatic 
nucleus  itself  may  be  protected  from  destruction  in  the  organism 
by  syntheses  with  other  bodies.  The  aromatic  ethereal  sulphuric 
acids  are  examples  of  this  kind. 

The  difficulty  in  deciding  whether  the  benzol  ring  itself  is 
destroyed  in  the  body  lies  in  the  fact  that  we  do  not  know  all  the 
different  aromatic  transformation  products  which  may  be  pro- 
duced by  the  introduction  of  any  aromatic  substance  in  the 
organism  and  which  we  must  seek  for  in  the  urine.  On  this 
account  it  is  also  impossible  to  learn  by  exact  quantitative  estima- 
tions whether  or  not  an  aromatic  substance  introduced  or  absorbed 
appears  again  in  its  entirety  in  the  urine.  Certain  observations 
render  it  probable  that  the  benzol  ring,  as  above  mentioned,  is  at 
least  in  certain  cases  destroyed  in  the  body.  Schotten"  and  Bau- 
MAiiTN"  have  found  that  certain  amido-acids,  such  as  tyrosin, 
phenylamido-propionic  acid  and  amido-cinnamic  acid,  when  intro- 
duced into  the  body  cause  no  increase  in  the  quantity  of  known 
aromatic  substances  in  the  urine;  this  makes  a  destruction  of  these 
amido-acids  in  the  animal  body  seem  probable.  Juvalta  also 
made  an  experiment  on  dogs  with  plithalic  acid  and  found 
that  57.5-680 76^  of  the  acid  introduced  into  the  body  disappeared, 
or  more  correctly  was  not  found  again.  According  to  Juvalta, 
this  acid  does  not  undergo  any  synthesis,  nor  does  it  yield  any 
aromatic  transformation  products;  and  if  this  supposition  be  correct, 
we  have  here  a  proof  of  the  destruction  of  the  benzol  nucleus  of  a 
part  of  the  phthalic  acid  introduced  into  the  organism  of  the  dor. 

An  oxidation  in  the  side  chain  of  aromatic  compounds  is  often 
found  and  may  also  occur  in  the  nucleus  itself.  As  an  example, 
benzol  is  first  oxidized  to  oxybenzol  (Schultzen  and  Naunyx), 
and  this  is  then  in  part  converted  into  dyoxybenzols  (Baumann"  and 
Peeusse).  XapMhalin  appears  to  be  converted  into  oxynaphtUalin 
and  probably  a  part  also  into  dioxynaphthalin  (Lesstib;  and  M. 
Nekcki).  Anilin,  C6H5.NH0,  passes  into  paramidophenol,  which 
passes  into  the  urine  as  ethereal  sulphuric  acid,  HgN.CgHi.O.SOa.OH 
(F.  Muller). 

If  the  aromatic  substance  has  a  side  chain  belonging  to  the  fatty 
series,  this  last  is  generally  oxidized.  For  example,  toluol,  G^'R-^.Qll^ 
(ScHULTZEif  and  Naunyn),  ethyl-benzol,  CgHj.CjHg,  and  propyl- 


392  PHYSIOLOGICAL   CHEMISTRY. 

benzol,  C6H5.C3H7  (jSTencki  and  Giacosa),  also  many  other  bodies 
are  oxidized  into  benzoic  acid.  If  the  side  chain  has  several  mem- 
bers, the  behavior  is  somewhat  different.  Plienyl-acetic  acid,  Q^^. 
CHg.COOH,  in  which  only  one  carbon  atom  exists  between  the 
benzol  nucleus  and  the  carboxyl,  is  not  oxidized,  but  is  eliminated 
after  coupling  with  glycocoll  as  plienacehtric  acid  (Salkowski). 
Plienyl-propionic  acid,  CeHg.CHa.CHa-COOHjWith  two  carbon  atoms 
between  the  benzol  nucleus  and  the  carboxyl  is,  on  the  contrary, 
oxidized  into  benzoic  acid.  Aromatic  amido-acids  with  three  car- 
bon atoms  in  the  side  chain,  and  where  the  NHg  group  is  bound  to 
the  middle  one,  as  in  tyrosin,  «;-oxyphenylamido-propionic  acid, 
C6H4(OH).CH2.CH(NH2).COOH,  and  a-phenylamido-propionic  acid, 
C6H5.CH2.CH(]SrH2).COOH,  seem  to  be  in  great  part  burnt  within 
the  body  (Schotten  and  Baumaxn).  Plienylamido-acetic  acid, 
which  has  only  two  carbon  atoms  in  the  side  chain,  06115.011(^112). 
OOOH,  acts  otherwise,  passing  into  mandelic  acid,  phenyl-glycolic 
acid,  06H5.0H(OH).OOOH  (Schotten). 

If  several  side  chains  are  present  in  the  benzol  nucleus,  then 
only  one  is  always  oxidized  into  carboxyl.  Thus  xylol,  0611^(0113)2 , 
is  oxidized  into  toluic  acid,  06H4(OH3)COOH  (Schultzen  and 
NAUJSTYiir),  mesitylen,  06H3(0H3)3 ,  into  mesitylenic  acid,  06113(0113)2. 
OOOH  (L.  Nencki),  and  cymol  into  cumic  acid  (M.  Nexcki  and 
Ziegler). 

Syntheses  of  aromatic  substances  with  other  atomic  groups 
occur  frequently.  To  these  syntheses  belongs,  in  the  first  rank, 
the  coupling  of  benzoic  acid  with  glycocoll  to  form  Mppuric 
acid,  first  discovered  by  Wohler.  All  the  numerous  aromatic  sub- 
stances which  are  converted  into  benzoic  acid  in  the  body  are 
voided  as  hippuric  acid.  This  statement  is  not  true  for  all  classes 
of  animals.  According  to  the  observations  of  Japfe,  benzoic  acid 
does  not  pass  into  hippuric  acid  in  birds,  but  into  another  more 
nitrogenized  acid,  ornitJntric  acid,  0191120^20^.  This  acid  yields  as 
splittiiig  products,  besides  benzoic  acid,  a  basic  body,  ornithin  (see 
page  389).  Oxyhenzoic  acids  (salicylic  acid  passes  partly  into  sali- 
cyluric acid)  and  the  substituted  benzoic  acids  form  pairs  with 
glycocoll  corresponding  to  hippuric  acid,  but  also  with  the  above- 
mentioned  acids,  toluic,  mesitylenic,  cumic,  and  plienyl-acetic  acid. 


THE  URINE.  393 

These  acids  are  voided  as  toluric,  mesitylenuric,  cuminuric,  and 
phenaceturic  acid. 

Another  synthesis  of  aromatic  substances  is  that  of  the  ethereal 
sulphuric  acids.  Phenol  and  chiefly  the  hydroxylated  aromatic 
hydrocarbons  are  voided  as  ethereal  sulphuric  acids,  according  to 
Baumann",  Heeter,  and  others. 

A  pairing  of  aromatic  substances  with  glycuronic  acid,  which 
last  is  protected  from  burning,  occurs  rather  often.  Gamplior^ 
CioHifiO,  when  given  to  a  dog,  is  first  converted  by  oxidation  into 
camphorol,  CioHi5(OH)0,  and  by  coupling  with  glycuronic  acid, 
camflio-glijcuronic  acid  is  produced  (Schmiedeberg).  Borneol 
and  menthol  give  directly,  with  the  elimination  of  water,  the  corre- 
sponding glycuronic  acids  (Pellacaki),  Phenol  may  also  be 
partly  voided  directly  as  a  coupled  glycuronic  acid  (Schmiedeberg). 
Naphthol  appears  in  great  part  to  pass  into  the  urine  as  coupled 
glycuronic  acids  (Lesxik  and  M.  Nencki).  Orthonitrotoluol  in 
dogs  passes  first  into  orthonitrobenzyl-alcohol  and  then  into  a 
coupled  glycuronic  acid  (Jaffe).  Indol  (Schmiedeberg)  and 
sJcatol  (Mester)  seem,  as  above  mentioned,  to  be  partly  voided 
by  the  urine  as  coupled  glycuronic  acids.  The  same  is  true  also 
for  many  other  aromatic  substances. 

A  synthesis  in  which  a  compound  containing  sulphur,  mercap- 
turic  acid,  occurs  is  produced  by  the  introduction  of  chlorine  or 
bromine  derivatives  of  benzol  into  the  organism  of  dogs  (Baumann" 
and  Preusse,  Jaffe).  C lilorhenzol  combines  with  cystein,  a  body 
which  seems  to  be  a  decomposition  product  of  the  albumins,  and 
which  is  nearly  related  to  cystin  (see  below),  forming  chlor- 
phenyJmercapturic  acid,  C11H12CISNO3.  On  boiling  with  a  mineral 
acid  this  compound  is  decomposed  into  acetic  acid  and  chlorphenyl- 
cystein,  CeHiCl.  CgHeNSO.,. 

P?/riVZ/«,  C5H5N,  which  does  not  combine  either  with  glycuronic 
acid  or  with  sulphuric  acid  after  previous  oxidation,  shows  a  special 
behavior.  It  takes  up  a  methyl  group  and  forms  an  ammonium 
combination,  methylpyi'idyl-ammoiiinm  hydroxyl  (His).  Several 
alkaloids,  such  as  quinin,  morpJiin,  and  strychnin,  may  pass  into 
the  urine.  After  taking  twpentine,  balsatn  of  copaiva,  and  resins 
these  may  pass  into  the  urine  as  resin  acids  (Maly).  Different 
kinds  of  coloring  matters,  such  as  alizarin,  crysophanic  acid,  after 


394  PHYSIOLOGICAL   CHEMISTRY. 

the  use  of  rhubarb  or  senna,  and  the  coloring  matter  of  the  blue- 
berry, may  pass  into  the  urine.  After  taking  rhubarb,  senna  or 
santonin  the  urine  takes  a  yellow  or  greenish-yellow  color,  which  is 
transformed  into  a  beautiful  red  color  by  the  addition  of  alkali. 
Phenol  produces,  as  above  mentioned,  a  dark-brown  or  dark -green 
color  which  depends  mainly  on  the  decomposition  products  of 
hydrochinon  or  humin  substances  (v.  Udranszky).  After  the  use 
of  naphthalin  the  urine  has  a  dark  color,  and  several  other  medi- 
cines produce  a  special  coloration.  Thus  cairin  gives  often  a  yel- 
lowish-green hue,  or  the  urine  darkens  when  exposed  to  the  air; 
thallin  gives  a  greenish-brown  color  which  is  marked  green  in  thin 
layers,  and  a7itipyrin  gives  a  yellow  to  blood-red.  After  the  admin- 
istration of  balsam  of  co-paiva  the  urine  becomes,  when  strongly 
acidified  with  hydrochloric  acid,  gradually  rose  and  purple-red 
(QuiisrcKE).  After  the  use  of  naphthalin  or  naphthol  the  urine 
gives  with  concentrated  sulphuric  acid  (1  c.  c.  concentrated  acid 
and  a  few  drops  of  urine)  a  beautiful  emerald-green  color  (Pen- 
zoldt),  which  is  probably  due  to  naphthol-glycuronic  acid.  Odor- 
iferous bodies  also  pass  into  the  urine.  After  eating  asparagus  the 
urine  acquires  a  sickly  disagreeable  odor.  After  taking  turpentine 
the  urine  may  have  a  peculiar  odor  similar  to  that  of  violets. 

VI.     Pathological  Constituents  of  Urine. 

Albumin.  The  appearance  of  slight  traces  of  albumin  in  the 
urine  of  apparently  healthy  persons  has  been  observed  in  many 
cases  by  several  investigators  (Leube,  Hofmeister,  Posner,  and 
others),  but  still  we  must  not  conceal  the  fact  that  other  investiga- 
tors consider  these  traces  of  albumin  as  the  first  symptoms,  though 
very  mild,  of  a  diseased  condition  of  the  urinary  apparatus,  or  as  a 
symptom  of  a  transitory  disturbance  in  the  circulation.  Frequently 
traces  are  found  in  the  urine  of  a  substance  similar  to  nucleoalbu- 
min  which  can  easily  be  mistaken  for  mucin  and  which  is  probably 
identical  with  nucleoalbumin.  This  substance  has  been  isolated 
from  the  pupillary  part  of  the  kidneys  and  from  the  mucous  mem- 
brane of  the  bladder  by  LoNifBERG.  In  diseased  conditions  albu- 
min occurs  in  the  urine  in  a  variety  of  cases.  The  albuminous 
bodies    which  most  often   occur  are    serum -globulin  and   serum- 


THE  URINE.  395 

albumin.  Albumoses  and  peptones  also  sometimes  occur.  The 
amount  of  albumin  in  the  urine  is  in  most  cases  less  than  5  p.  m., 
rarely  10  p.  m.,  and  only  very  rarely  does  it  amount  to  50  p.  m.  or 
over. 

Among  the  many  reactions  proposed  for  the  detection  of  albu- 
min in  urine,  the  following  are  to  be  recommended  : 

TJie  Heat  Test.  Filter  the  urine  and  test  its  reaction.  An  acid 
urine  may,  as  a  rule,  be  boiled  without  further  treatment,  and  only 
in  especially  acid  urines  is  it  necessary  to  first  treat  with  a  little 
alkali.  An  alkaline  urine  is  made  neutral  or  faintly  acid  before 
heating.  If  the  urine  is  poor  in  salts,  add  J^-  vol.  of  a  saturated 
common-salt  solution  before  boiling;  then  heat  to  boiling  point, 
and  if  no  precipitation,  cloudiness,  or  opalescence  appears,  the 
urine  in  question  contains  no  coagulable  albumin,  but  it  may  con- 
tain albumoses  or  peptones.  If  a  precii^itate  is  jaroduced  on  boil- 
ing, this  may  consist  of  albumin,  or  of  earthy  phosphates,  or  of 
both.  The  simple-acid  calcium  phosphate  decomposes  on  boiling, 
and  normal  phosphate  may  separate  (Stokvis,  Salkowski,  Ott). 
The  proper  amount  of  acid  is  now  added  to  the  urine,  so  as  to  pre- 
vent any  mistake  caused  by  tlie  presence  of  eartliy  phosphates,  and 
to  give  a  better  and  more  flocculent  precipitate  of  the  albumjn.  If 
acetic  acid  is  used  for  this,  then  add  1-2-3  drops  of  a  25^  acid  to 
each  10  c.  c.  of  the  urine,  and  boil  after  the  addition  of  each  drop. 
On  using  nitric  acid,  add  1-2  drops  of  the  25^  acid  to  each  c.  c.  of 
the  boiling-hot  uriue. 

On  using  acetic  acid,wlien  tlie  amount  of  albumin  is  very  small, 
and  especially  when  the  urine  was  originally  alkaline,  the  albumin 
may  sometimes  remain  in  solution  on  the  addition  of  the  above 
quantity  of  acetic  acid.  If,  on  the  contrary,  less  acid  is  added,  the 
precipitate  of  calcium  phosphate,  which  forms  in  amphoteric  or 
faintly-acid  urines,  is  liable  not  to  dissolve  completely,  and  this 
may  cause  it  to  be  mistaken  for  an  albumin  jjrecipitate.  If  nitric 
acid  is  Used  for  the  heat  test,  the  fact  must  not  be  overlooked  that 
after  the  addition  of  only  a  little  acid  a  combination  between  it 
and  the  albumin  is  formed  which  is  soluble  while  boiling  and 
which  is  only  precipitated  by  an  excess  of  the  acid.  On  this  account 
the  large  amount  of  nitric  acid  as  suggested  above  must  be  added, 
but  in  this  case  a  small  part  of  the  albumin  is  liable  to  be  dissolved 
by  the  excess  of  the  nitric  acid.  When  the  acid  is  added  after  boil- 
ing, which  is  absolutely  necessary,  the  liability  of  a  mistake  is  not 
so  great.  It  is  on  these  grounds  that  the  heat  test,  although  it 
gives  very  good  results  in  the  hands  of  experts,  is  not  recommended 
to  physicians  as  a  positive  test  for  albumin. 

A  confounding  with  mucin,  when  this  body  occurs  in  the  urine. 


396  PHYSIOLOGICAL   CHEMISTRT. 

is  easily  prevented  in  the  heat  test  with  acetic  acid,  by  acidifying 
another  portion  with  acetic  acid  at  the  ordinary  temperature.  Mucin 
and  nucleoalbumin  substances  similar  to  mucin  are  hereby  precipi- 
tated. If  in  the  performance  of  the  heat  and  nitric  acid  test  a 
precipitate  first  appears  on  cooling  or  is  strikingly  increased,  then 
this  siiows  the  presence  of  albumoses  in  the  urine,  either  alone  or 
mixed  with  coagulable  albumin.  In  this  case  a  further  investiga- 
tion is  necessary  (see  below).  In  a  urine  rich  in  urates  a  precipi- 
tate consisting  of  uric  acid  separates  on  cooling.  This  precipitate 
is  colored,  sandy,  and  hardly  to  be  mistaken  for  an  albumose  or 
albumin  precipitate. 

Hellee's  test  is  performed  as  follows  (see  page  19) :  The  urine 
is  very  carefully  floated  on  the  surface  of  nitric  acid  in  a  test-glass. 
The  presence  of  albumin  is  shown  by  a  white  ring  between  the 
two  liquids.  With  this  test  a  red  or  reddish-violet  ring  is  always 
obtained  with  normal  urine;  it  depends  on  the  indigo  coloring  mat- 
ters and  can  hardly  be  mistaken  for  the  white  or  whitish  albumin 
ring,  and  this  last  must  not  be  mistaken  for  the  ring  produced  by 
bile- pigments.  In  a  urine  rich  in  urates  another  complication  may 
occur,  due  to  the  formation  of  a  ring  produced  by  the  precipitated 
uric  acid.  The  uric-acid  ring  does  not  lie,  like  the  albumin  ring, 
between  the  two  liquids,  but  somewhat  higher.  For  this  reason  we 
may  often  have  two  simultaneous  rings  with  urines  rich  in  urates 
and  yet  not  containing  very  much  albumin.  The  disturbance 
caused  by  uric  acid  is  easily  prevented  by  diluting  the  urine 
with  1-2  vol.  water  before  performing  the  test.  The  uric  acid  now 
remains  in  solution,  and  the  delicacy  of  Heller's  test  is  so  great 
that  after  dilution  only  in  the  presence  of  insignificant  traces  of 
albumin  does  this  test  give  negative  results.  In  a  urine  very  rich 
in  urea  a  ring-like  separation  of  urea  nitrate  may  also  appear.  This 
ring  consists  of  shining  crystals,  and  it  does  not  appear  in  the  pre- 
viously-diluted urine.  A  confusfon  with  resinous  acids,  which  also 
give  a  whitish  ring  with  this  test,  is  easily  prevented,  since  these 
acids  are  soluble  on  the  addition  of  alcohol.  A  liquid  which  con- 
tains pure  mucin  does  not  give  a  precipitate  with  this  test,  but  it 
gives  a  more  or  less  strongly  opalescent  ring,  which  disappears  on 
stirring.  The  liquid  does  not  contain  any  precipitate  after  stirring, 
but  is  clear  or  somewhat  opalescent.  If  we  bear  in  mind  the 
above-mentioned  possible  mistakes  and  the  means  by  which  they 
may  be  prevented,  there  is  hardly  another  test  for  albumin  in  the 
urine  which  is  at  the  same  time  so  easily  performed,  so  delicate,  and 
so  positive  as  Heller's.  With  this  test  even  0.02  p.  m.  albumin 
may  be  detected  without  difficulty.  In  performing  this  test  the 
(primary)  albumoses  are  also  precipitated. 

The  reaction  with  metaphosplwric  acid  (see  page  19)  is  very 
convenient  and  easily  performed.     It  is  not  quite  so  delicate  and 


^ 


THE   URINE.  397 

positive  as  Heller's  test.  The  albumoses  are  also  precipitated 
by  this  reageut. 

Reaction  with  Acetic  Acid  and  Potassium  Ferrocyanide.  Treat 
the  urine  first  with  acetic  acid  of  about  2^  and  then  add  drop  by 
drop  a  potassium  ferrocyanide  sohition  (1:20),  carefully  avoiding 
an  excess.  This  test  is  very  good,  and  in  the  hands  of  experts  it 
is  even  more  delicate  than  Heller's.  In  the  presence  of  very 
small  amounts  of  albumin  it  requires  more  practice  and  dexterity 
than  Heller's,  as  the  relative  quantities  of  reagent  to  the  albumin 
act  on  the  result  of  the  test.  The  amount  of  salts  in  the  urine 
also  seems  to  have  an  influence.  This  reagent  also  precipitates 
albumoses. 

The  different  color  reactions  cannot  be  directly  used,  especially 
in  deep-colored  urines  which  only  contain  little  albumin.  The 
common  salt  of  the  urine  has  a  disturbing  action  on  Millon's 
reagent.  To  prove  more  positively  the  presence  of  albumin,  the 
precipitate  obtained  in  the  boiling  test  may  be  filtered,  washed, 
and  then  tested  with  Millon's  reagent.  The  precipitate  may  also 
be  dissolved  in  dilute  alkali  and  the  biuret  test  applied  to  the  solu- 
tion. The  presence  of  albumoses  or  peptones  in  the  urine  is 
directly  tested  for  by  this  last-mentioned  test.  In  testing  the 
urine  for  albumin  one  must  never  be  satisfied  with  one  test  alone, 
but  one  must  at  least  apply  the  heat  test  and  Heller's  test  or  the 
potassium-ferrocyanide  test.  In  using  the  heat  test  alone  the 
albumoses  may  be  easily  overlooked,  but  these  are  detected,  on  the 
contrary,  by  Heller's  test.  If  we  are  satisfied  with  this  last  test 
or  the  potassium-ferrocyanide  test  alone,  we  have  no  sufficient  inti- 
mation of  the  kind  of  albumin  present,  whether  it  consists  of  albu- 
moses or  coagulable  albumin. 

For  practical  purposes  several  dry  reagents  for  albumin  bave  been  recom- 
mended. Besides  the  metaphosphoric  acid  may  be  mentioned  :  Pavy's  re- 
agent, which  consists  of  small  disks  or  plates  of  citric  acid  and  sodium  ferrocy- 
anide ;  Stutz's  or  FiJRBRiNGER's  gelatine  capsules,  which  contain  mercuric 
chloride,  sodium  chloride,  and  citric  acid;  and  Geissler's  albumin-test  papers, 
which  consist  of  strips  of  filter-paper  which  have  been  dipped  in  a  solution 
of  citric  acid  and  also  mercuric  chloride  and  potassium-iodide  solution  and 
then  dried. 

If  the  presence  of  albumin  has  been  positively  proved  in  the 
urine  by  the  above  tests,  it  then  remains  necessary  to  determine  the 
variety. 

The  detection  of  globulin  and  albu7nin.  In  detecting  serum- 
globulin  the  urine  is  exactly  neutralized,  filtered,  and  treated  with 
magnesium  sulphate  in  substance  until  it  is  completely  saturated 
at  the  ordinary  temperature,  or  with  an  equal  volume  of  a  saturated 
neutral  solution  of  ammonium  sulphate.  In  both  cases  a  white, 
flocculent  precipitate  is  formed  in  the  presence  of  globulin.     In 


398  PHYSIOLOGICAL  CHEMISTRY. 

using  ammonium  sulphate  with  a  urine  ricli  in  urates  a  precipitate 
consisting  of  ammonium  urate  may  separate.  This  precipitate  does 
not  appear  immediately,  but  only  after  a  certain  time,  and  it  must 
not  be  mistaken  for  the  globulin  precipitate.  In  detecing  serum 
albumin  heat  the  filtrate  from  the  globulin  precipitate  to  boiling- 
point  or  add  about  1^  acetic  acid  to  it  at  the  ordinary  temperature. 
In  detecting  albumoses,  whose  occurrence  in  the  urine  was  first 
shown  by  Bence  Jones  and  by  Klthne  and  later  observed  by 
many  investigators  in  different  diseased  conditions,  first  remove  all 
coagulable  albumins,  if  any  are  present,  by  boiling  with  the  addi- 
tion of  acetic  acid.  The  filtrate  is  then  tested  by  the  biuret  test, 
and  when  this  gives  positive  results  apply  the  three  above-men- 
tioned albumose  reagents  (page  26),  nitric  acid,  acetic  acid,  and 
potassium  ferrocyanide,  and  saturate  with  common  salt  with  the 
addition  of  acid.  The  albumoses  may  also  be  precipitated  by  sat- 
urating with  ammonium  sulphate  in  substance. 

Peptones,  as  shown  by  the  experiments  of  several  investigators, 
among  whom  should  be  especially  mentioned  Hofmeister,  v. 
Jaksch,  Maixker,  and  Fischel,  may  appear  in  the  urine  as  soon 
as  it  occurs  dissolved  in  the  blood.  This  is  especially  the  case  in 
an  abundant  destruction  of  the  pus-cells  with  absorption  of  the 
peptones  originating  therefrom,  as  also  in  pneumonia,  in  purulent 
pleuritis,  etc.  (pyogen'e  peptonuria,  Hofmeister,  Maixner,  v. 
Jaksch).  Peptone  also  passes  into  the  urine  when  the  normal 
absorption  and  assimilation  of  the  peptones  is  disturbed  so  that 
the  peptones  pass  directly  through  the  destroyed  part  of  the  intes- 
tine into  the  blood,  as  in  ulcerous  processes  in  the.intestine  (ejstter- 
OGENic  peptonuria,  Mixner),  also  in  puerperal  peptonuria 
(Fischel),  in  acute  phosphorus-poisoning  and  certain  diseases  of  the 
liver  (hepatogenic  peptonuria),  in  effusion  of  blood  in  difficult 
cases  of  scurvy  (h.ematogenic  peptonuria,  v.  Jaksch),  etc.  etc. 

These  statements  refer  only  to  the  peptone  in  the  old  sense,  and 
the  question  as  to  whether  we  are  dealing  with  "secondary  albu- 
moses "  or  with  "  pure  peptones"  or  a  mixture  of  both  is  still  un- 
decided. Until  we  are  agreed  as  to  the  importance  of  the  peptones 
and  albumoses  it  is  hardly  possible  to  give  positive  statements  in 
regard  to  the  occurrence  of  peptones  in  the  urine,  or  to  give  ac- 
curate methods  for  their  detection  and  quantitative  estimation. 

The  urine  to  he  testeri  for  peptone  in  the  old  sense  must  be  free  from 
mucin  and  from  albumin  so  that  it  does  not  give  either  the  potassium-ferro- 


THE   URINE.  399 

■cyanide  reaction  or  Heller's  test.  Such  a  urine  may  be  tested  directly ;  if, 
on  the  contrary,  it  contains  albumin,  this  must  first  be  removed.  This  is 
ordinarily  done  according  to  Hofmeistek's  method.  At  least  half  a  litre  of 
the  urine  is  treated  with  an  excess  of  a  lead-acetate  solution,  or  with  only  a 
quantity  sutticieut  to  produce  a  dense  tiocculeut  precipitate  in  order  to  separate 
some  so-called  mucin  present  as  well  as  a  part  of  the  albumin  and  coloring 
matters.  If  the  operation  has  been  well  conducted,  the  filtrate,  which  gives  a 
precipitate  with  more  lead-acetate  solution,  is  tested  for  albumin.  In  the 
aljseuce  of  this  it  is  directly  tested  for  peptone  ;  but  if  albumin  be  present,  it 
must  first  be  removed  by  boiling  with  ferric-acetate  solution.  For  this  pur- 
pose treat  the  filtrate  with  a  concentrated  sodium -acetate  solution  (about  10 
c.  c.  for  ^  litre  urine;  and  then  with  ferric-chloride  solution  until  it  has  a 
blood-red  color.  The  acid-reacting  liquid  is  then  rendered  neutral  or  faintly 
acid  by  means  of  the  addition  of  alkali,  boiled  strongly,  and  filtered  after 
cooling.  The  filtrate  should  be  free  from  albumin  ;  but" if  that  is  not  the  case, 
it  must  be  repeatedly  treated  with  sodium  acetate  and  ferric  chloride.  If  the 
urine  to  be  tested  for  peptones  is  rather  rich  in  albumin  at  first,  the  albumin 
must  be  removed  as  far  as  possible  by  boiling  with  the  addition  of  acetic  acid 
before  it  is  treated  with  lead-acetate  solution  as  above  described. 

A  small  portion  of  the  filtrate  entirely  free  from  albumin  is  taken,  made 
strongl}'  acid  with  acetic  acid  and  then  treated  with  an  acetic-acid  solution  of 
phospho-tungstic  acid.  If  the  test  remains  clear  for  some  time,  the  urine  con- 
tains no  peptones  ;  but  if  a  milky  cloudiness  occurs,  peptones  may  be  present 
and  the  filtrate  must  be  further  treated. 

For  this  purpose  add  yt-^^  vol.  concentrated  hydrochloric  acid  and  then 
add  a  phospho-tungstic  acid  solution  treated  with  acid  as  long  as  a  precipitate 
is  produced.  This  is  quickly  filtered  and  treated  with  water  which  contains 
3-5g  concentrated  sulphuric  acid,  washed,  until  the  filtrate  is  colorless.  The 
still  moist  precipitate  is  thoroughly  rubbed  with  an  excess  of  solid  barium 
hydrate,  some  water  added,  gently  warmed  for  a  time,  and  filtered.  The 
peptones  (and  secondary  albumoses)  are  detected  in  the  filtrate  by  applying 
the  previously-mentioned  reactions.  Special  stress  must  be  laid  on  the  biuret 
reaction,  which  is  used  also  as  a  colorimetric  quantitative  test  for  peptones. 

In  detecting  pure  peptones  the  solution  must  be  saturated  with  ammonium 
sulphate  while  boiling,  and  filtered  at  the  same  temperature.  After  cooling 
remove  the  liquid  from  the  deposited  crystals,  dilute  strongly,  precipitate  the 
peptone  by  the  careful  addition  of  tannic  acid,  treat  the  precipitate  with  an 
excess  of  "barium  hydrate,  and  use  the  filtrate  in  which  the  excess  of  dissolved 
barium  hydrate  has  been  removed  by  COo  for  the  biuret  test.  Still  by  this 
procedure  the  peptones  may  be  contaminated  by  some  albumoses.  We  have 
no  very  exact  method  for  the  quantitative  estimation  of  albumose  or  peptones 
in  the  urine. 

Qnajititative  Estimation  of  Albumin  in  Urine.  Of  all  the 
methods  proposed  thus  far,  the  coagulatiox  method  (boiling  with 
the  addition  of  acetic  acid)  wheu  performed  with  sufficient  care 
gives  the  best  results.  The  average  errors  need  never  amount  to 
more  than  0.01'i^,  and  it  is  generally  smaller.  In  using  this  method 
it  is  best  to  first  find  how  much  acetic  acid  must  be  added  to  a 
small  portion  of  urine,  which  has  been  previously  heated  on  the 
water-bath,  to  completely  separate  the  albumin,  so  that  the  filtrate 
does  not  respond  to  Heller's  test.  Then  coagulate  20-50-100 
c.  c.  of  the  urine.  Pour  the  urine  into  a  beaker  and  heat  on  the 
water-bath,  add  the  required  quantity  of  acetic  acid  slowly,  stirring 


400  PHYSIOLOGICAL   CHEMISTRY. 

constantly  and  heating  at  the  same  time.  Filter  while  warm, 
wash  first  with  water,  then  with  alcohol  and  ether,  dry  and  weigh, 
ash  and  weigh  again.  In  exact  determinations  the  filtrate  must 
not  give  Heller's  test. 

The  separate  estimation  of  globulins  and  Albumin's  is  done 
by  carefully  neutralizing  the  urine  and  precipitating  with  MgSO^ 
added  to  saturation  (author),  or  simply  by  adding  an  equal 
volume  of  a  saturated  neutral  solution  of  ammonium  sulphate 
(HoFMEiSTER  and  Pohl).  The  precipitate  consisting  of  globulin 
is  thoroughly  washed  with  a  saturated  magnesium  sulphate  or  half- 
saturated  ammonium-sulphate  solution,  dried  continuously  at  110° 
C,  boiled  with  water,  extracted  with  alcohol  and  ether,  then  dried, 
weighed,  ashed,  and  weighed  again.  The  quantity  of  albumin  is 
calculated  as  the  difference  between  the  quantity  of  globulins  and 
the  total  proteids. 

Apjn'oximate  Estimation  of  Albumin  in  Urine.  Of  the  methods 
suggested  for  this  purpose  none  has  been  more  extensively  employed 
than  Esbach's. 

Esbach's  m,ethod.  The  acidified  urine  (acidified  with  acetic 
acid)  is  poured  into  a  specially-graduated  tube  to  a  certain  mark 
and  then  the  reagent  (a  '2<fo  citric-acid  and  l<fo  picric-acid  solution 
in  water)  is  added  to  a  second  mark,  the  tube  is  closed  with  a 
rubber  stopper  and  carefully  shaken,  avoiding  the  production  of 
froth.  The  tube  is  allowed  to  stand  twenty-four  hours,  and  then 
the  height  of  the  precipitate  in  the  graduated  tube  is  read  off. 
The  reading  gives  directly  the  quantity  of  albumin  in  1000  parts  of 
the  urine.  Urines  rich  in  albumin  must  first  be  diluted  with  water. 
The  results  obtained  by  this  method  are,  however,  dependent  upon 
.the  temperature;  and  a  difference  in  temperature  of  5°  to  6.5°  C. 
may  in  urines  containing  a  medium  quantity  of  albumin  cause  an 
error  of  0.2-0.3^  deficiency  or  excess  (Christetstsef  and  Mygge). 
This  method  is  only  to  be  used  in  a  room  in  which  the  temperature 
may  be  kept  nearly  constant.  The  directions  for  the  use  of  the 
apparatus  accompany  it. 

Christensen's  and  Mygge's  method.  5  c.  c.  of  urine,  after 
being  acidified  with  2  drops  of  acetic  acid,  are  poured  into  a  some- 
what modified  burette  and  precipitated  with  a  certain  quantity  of 
a  I'fo  tannic-acid  solution  and  then  treated  with  1  c.  c.  of  mucilage. 
After  the  addition  of  water  to  a  certain  mark  and  after  inverting 
the  tube  several  times  a  uniform  emulsion  is  produced.  A  cylin- 
drical ghiss  filled  one  half  or  one  third  with  water  is  now  placed  on 
a  white  surface  having  a  number  of  close  black  lines  traced  upon  it, 
and  the  contents  of  the  burette  are  gradually  added  to  the  water 
with  constant  stirring,  until  by  close  observation  the  black  lines 
cannot  even  be  distinguished  from  the  white  spaces.  The  reading 
of  the   amount   of   urine   emulsion   employed   gives   directly  the 


THE  URINE.  401 

amount  of  albumin  in  the  urine.  This  method  is  claimed  to  give 
very  good  results.  A  special  description  accompanies  each  ap- 
paratus. 

The  method  proposed  by  Roberts  and  Stolnikow  and  further  developed 
by  Brandberg,  though  somewhat  more  dithcult  to  perform,  also  gives  satis- 
factory results.  The  density  methods  of  Lang,  Huppert,  aud  Zahor  are 
also  very  good.  The  last  consists  in  determining  the  specific  gravity  before 
and  after  the  coagulation  of  the  albumins. 

Mucin  occurs  in  the  urine  under  normal  conditions  partly  dissolved  and 
partly  in  a  strongly-distended,  finely-divided  stale.  It  appears  in  greatest 
amounts  in  catarrhal  afl'ectious  of  the  uriuary  passages.  The  occurrence  of 
pure  mucin  in  the  urine  has  thus  far  not  been  positively  shown. 

To  detect  mucin  in  urine  first  dilute  with  water,  partly  to  prevent  the  pre- 
cipitation of  uric  acid  on  the  subsequent  addition  of  acid,  and  partly  to 
diminish  the  solubility  of  the  mucin  in  the  common  salt  of  the  uriue.  Now 
add  an  excess  of  acetic  acid.  The  precipitate  formed  is  purified  by  dissolving 
in  water  with  the  addition  of  a  little  alkali  aud  reprecipitated  with  acetic  acid. 
The  precipitate  is  tested  with  the  ordinary  mucin  reagents.  To  avoid  mistak- 
ing mucin  for  nucleoalbumin,  which  is  similar  to  mucin,  the  precipitate  must 
be  tested  in  regard  to  its  behavior  on  boiling  with  dilute  mineral  acids.  If  no 
reducible  substance  is  formed  by  this  treatment,  it  contains  no  mucin. 

Blood  and  Blood-coloring  Matters.  The  urine  may  contain 
blood  from  hemorrhage  in  the  kidneys  or  other  parts  of  the  urinary 
passages  (h^ematueia).  In  these  cases,  when  the  quantity  of  blood 
is  not  very  small,  the  urine  is  more  or  less  cloudy  and  colored 
reddish,  yellowish  red,  dirty  red,  brownish  red,  or  dark  brown. 
In  recent  hemorrhages,  in  which  the  blood  has  not  decomposed, 
the  color  is  nearer  blood-red.  Blood-corpuscles  may  be  found  in 
the  sediment,  sometimes  also  blood-cylinders  and  smaller  or  larger 
blood -clots. 

In  certain  cases  the  urine  contains  no  blood-corpuscles,  but  only 
dissolved  blood-coloring  matters,  haemoglobin,  or,  and  indeed  quite 
often,  methsemoglobin  (hemoglobinuria).  The  blood-coloring 
matters  appear  in  the  urine  under  different  conditions,  as  in  dissolu- 
tion of  blood  in  poisoning  with  arseniuretted  hydrogen,  chlorates, 
etc.,  after  serious  burns,  after  transfusion  of  blood,  and  also  in  the 
periodic  appearance  of  haemoglobinuria  with  fever.  The  urine  may 
in  haBmoglobinuria  also  have  an  abundant  grayish-brown  sediment 
rich  in  albumin  which  contains  the  remains  of  the  stromata  of 
the  red  blood-corpuscles.  In  animals  haemoglobinuria  may  be 
produced  by  many  causes  which  force  free  haemoglobin  into  the 
plasma. 

To  detect  blood  in  the  urine  we  make  use  of  the  microscope. 


402  PHYSIOLOGICAL   CHEMISTRY. 

spectroscope,  the  guaiacum  test,  and  Hellek's  or  Hellee- 
Teichmainn's  test. 

Microscopic  Investigation.  The  blood-corpuscles  may  remain 
undissolved  for  a  long  time  in  acid  urine  ;  in  alkaline  urine,  on  the 
contrary,  they  are  easily  changed  and  dissolved.  They  often 
appear  entirely  unchanged  in  the  sediment ;  in  some  cases  they  are 
distended,  and  in  others  unequally  pointed  or  jagged  like  a  thorn- 
apple.  In  hemorrhage  of  the  kidneys  a  cylindrical  clot  is  some- 
times found  in  the  sediment  which  is  covered  with  numerous  red 
blood-corpuscles,  forming  casts  of  the  urinary  passages.  These 
formations  are  called  blood-cylindeks. 

The  spectroscojyic  investigatioji  is  naturally  of  very  great  value; 
and  if  it  be  necessary  to  determine  not  only  the  presence  but  also 
the  kind  of  coloring  matter,  this  method  is  indispensable.  In 
regard  to  the  optical  behavior  of  the  various  blood-coloring  matters 
we  must  refer  to  Chapter  IV. 

Almen's  Guaiacum  Test.  Mix  in  a  test-tube  equal  volumes  of 
tincture  of  guaiacum  and  old  turpentine  which  has  become  strongly 
ozonized  by  the  action  of  air  under  the  influence  of  light.  To  this 
mixture,  which  must  not  have  the  slightest  blue  color,  add  the  urine 
to  be  tested.  In  the  presence  of  blood  or  blood-coloring  matters, 
first  a  bluish-green  and  then  a  beautiful  blue  ring  appears  where 
the  two  liquids  meet.  On  shaking  the  mixture  it  becomes  more  or 
less  blue.  Normal  urine  or  one  containing  albumin  does  not  give 
this  reaction.  For  the  reason  of  this  we  must  refer  the  reader  to 
Chapter  IV,  page  71.  Urine  containing  pus,  although  no  blood  is 
present,  gives  a  blue  color  with  these  reagents  ;  but  in  this  case  the 
tincture  of  guaiacum  alone,  without  turpentine,  is  colored  blue  by 
the  urine  (Vitalli).  This  is  at  least  true  for  a  tincture  that  has 
been  exposed  for  some  time  to  the  action  of  air  and  sunlight. 
The  blue  color  produced  by  pus  differs  from  that  produced  by 
blood-coloring  matters  by  disappearing  on  heating  the  urine  to 
boiling.  A  urine  alkaline  by  decomposition  must  first  be  made 
faintly  acid  before  performing  the  reaction.  The  turpentine  should 
be  kept  exposed  to  sunlight,  while  the  tincture  of  guaiacum  mustJbe 
kept  in  a  dark  glass  bottle.  These  reagents  to  be  of  use  must  be 
•controlled  by  a  liquid  containing  blood.  This  test,  it  is  true,  in 
positive  results  is  not  absolutely  decisive,  because  other  bodies  may 


THE   URINE.  403 

.give  a  blue  reaction  ;  but  when  properly  performed  it  is  so  extremely 
delicate  that  when  it  gives  negative  results  any  other  test  for  blood 
is  superfluous. 

Hellee-Teichmann's  Test.  If  a  neutral  or  faintly-acid  urine 
containing  blood  is  heated  to  boiling,  we  always  obtain  a  mottled 
precipitate  consisting  of  albumin  and  haematin.  If  caustic  soda  is 
added  to  the  boiling-hot  test,  the  liquid  becomes  clear  and  turns 
green  when  examined  in  thin  layers  (due  to  haematin  alkali),  and 
a  red  precipitate,  appearing  green  by  reflected  ligiit,  ]-e-forms 
which  consists  of  earthy  pliosphates  and  hsematin.  This  reaction  is 
called  Heller's  blood-test.  If  this  precipitate  is  collected  after  a 
time  on  a  small  filter,  it  may  be  used  for  the  hsemin  test  (see 
page  79).  If  the  precipitate  contains  only  a  little  blood-coloring 
matter  with  a  larger  quantity  of  earthy  phosphates,  then  wash  it 
with  dilute  acetic  acid,  which  dissolves  the  earthy  phosphates,  and 
use  the  residue  for  the  preparation  of  Teichmakn's  haemin 
crystals.  If,  on  the  contrary,  the  amount  of  phosphates  is  very 
small,  then  first  add  a  little  CaClj  solution  to  the  urine,  heat  to 
boiling,  and  add  simultaneously  with  the  caustic  potash  some  sodium- 
phospiiate  solution.  In  the  presence  of  only  very  small  amounts  of 
blood,  first  make  the  urine  very  faintly  alkaline  with  ammonia,  add 
tannic  acid,  acidify  with  acetic  acid,  and  use  the  precipitate  in  the 
preparation  of  the  haemin  crystals  (Stkuve). 

Melanin.  In  the  presence  of  melanotic  cancers  sometimes  dark  coloring 
matters  are  eliminated  with  the  urine.  K.  Morner  has  isolated  two  coloring 
matters  from  such  a  iirine,  of  which  one  was  soluble  in  warm  50-75^  acetic 
acid  and  the  other,  on  the  contrary,  was  insoluble.  Tlie  one  seemed  to  be 
phymat07'usin{see  page  324).  Usually  the  urine  does  not  contain  any  melanin, 
but  a  chromogen  of  melanin,  melanogen.  In  such  cases  the  urine  gives  Eiselt's 
reaction,  becoming  dark-colored  with  oxidizing  agents  such  as  cone,  nitric- 
acid,  potassium  bichromate,  and  sulphuric  acid,  as  well  as  with  free  sulphuric 
acid.  Urine  containing  melanin  or  melanogen  is  colored  black  by  ferric- 
cliloride  solution  (Jaksch). 

Baumstark  found  in  a  case  of  leprosy  two  characteristic  coloring  matters 
in  the  urine,  "  urorubrohsematin  "  and  "  urof  iiscohfematin,"  which,  as  their 
names  indicate,  seem  to  stand  in  close  relationship  to  the  blood-coloring  matters. 

Urorubroh(Bmatin,  CosHgjNgFe-jO.iB ,  contains  iron  and  shows  an  absorption- 
band  in  front  of  D  and  one  broader  back  of  D.  In  alkaline  solution  it  shows 
four  bands,  behind  D,  at  E,  beyond  F,  and  behind  O.  It  is  not  soluble  either 
in  water,  alcohol,  ether,  or  chloroform.  It  gives  a  beautiful  brownish-red 
non-dichroitic  liquid  with  alkalies.  Urofuscohmmatin,  CesHiosNgOae ,  which 
is  free  from  iron  shows  no  characteristic  spectrum  ;  it  dissolves  in  alkalies,  pro- 
ducing a  brown  color. 

,.  Urorosein,  so  named  by  Nencki.  is  a  urinary  coloring  matter,  occurring  in 
various  diseases,  which  appears  on  the  acidification  of  the  urine  with  a  mineral 
acid,  and  which  is  taken  up  by  shaking  with  amyl-alcohol.  The  solution  shows 
an  absorption-band  between  D  and  E  TJroerythrin,  which  gives  a  rose-red 
color  to  the  urinary  sediments  especially  in  fevers,  seems  to  occur  also  in  urine 
under  physiological  conditions.      It  iias  not  been  thoroughly  studied.     A 


404  PHYSIOLOGICAL  CHEMI8TET. 

coloring  matter  nearly  related  to  hcBmatoporphyrin  has  been  found  by  Neusser. 
in  two  pathological  urines.  MacMunn  has  found  a  coloring  matter,  uroJmma-^ 
iin,  in  rheumatism  and  Addison's  disease  ;  he  also  prepared  it  artificially  from 
hsematin.  This  coloring  matter  seems  also  to  stand  in  close  relationship  to> 
hsematoporphyrin. 

Pus  occurs  in  the  urine  in  different  inflammatory  affections, 
especially  in  catarrh  of  the  bladder  and  in  inflammation  of  the  mem- 
brane of  the  kidneys  or  the  urethra. 

Pus  is  best  detected  by  means  of  the  microscope.  The  pus-cells 
are  rather  easily  destroyed  in  alkaline  urines.  In  detecting  pus  we 
make  use  of  Doe^ne's  pus-test,  which  is  performed  in  the  following 
way:  Pour  off  the  urine  from  the  sediment  as  carefully  as  possible, 
place  a  small  piece  of  caustic  alkali  on  the  sediment,  and  stir.  If 
the  pus-cells  have  not  been  previously  changed,  the  sediment  is 
converted  by  this  means  into  a  slimy  tough  mass. 

The  pus-corpuscles  swell  up  in  alkaline  urines,  dissolve,  or  at 
least  are  so  changed  that  they  cannot  be  recognized  under  the  mi- 
croscope. The  urine  in  these  cases  is  more  or  less  slimy  or  fibrous, 
and  it  is  precipitated  in  large  flakes  by  acetic  acid,  so  that  it  may 
possibly  be  mistaken  for  mucin.  The  closer  investigation  of  the 
precipitate  produced  by  acetic  acid,  and  especially  the  appearance 
or  non-appearance  of  a  reducible  substance  after  boiling  it  with  a 
mineral  acid,  demonstrates  the  nature  of  the  precipitated  substance. 
Urine  containing  pus  always  contains  albumin. 

Bile-acids.  The  statements  in  regard  to  the  occurrence  of  bile- 
acids  in  the  urine  under  physiological  conditions  do  not  agree. 
According  to  Vogel  and  Deagendoeff  and  vHMPtraces  of  bile- 
acids  occur  in  the  urine;  according  to  Hoppe-Seyler  and  v. 
Udr^kszkt,  they  do  not.  Pathologically  they  are  present  in  the 
urine  in  hepatogenic  icterus,  although  not  always. 

Detection  of  Bile-acids  in  the  urine.  Pettenkofer's  test  gives 
always  the  most  decisive  reaction ;  but  as  it  gives  similar  color  re- 
actions with  other  bodies,  it  must  be  supplemented  by  the  spectro- 
scopic investigation.  The  direct  test  for  bile-acids  is  easy  after  the 
addition  of  traces  of  bile  to  a  normal  urine.  But  the  direct  detec- 
tion in  a  colored  icteric  urine  is  more  difficult  and  gives  very  mis- 
leading results;  the  bile-acid  must  therefore  always  be  isolated  from 
the  urine.  This  may  be  done  by  the  following  method  of  Hoppe- 
Seyler,  which  is  slightly  modified  in  non-essential  points. 

Hoppe-Seyler's  Method.  Strongly  concentrate  the  urine,  and 
extract  the  residue  with  strong  alcohol.  The  filtrate  is  freed  from 
alcohol  by  evaporation  and  then  precipitated  by  basic  lead  acetate 
and  ammonia.  The  washed  precipitate  is  treated  with  boiling  al- 
cohol, filtered  hot,  the  filtrate  treated  with  a  few  drops  of  soda  solu- 


THE  URINE.  405 

tion,  and  evaporated  to  dryness.  The  dry  residue  is  extracted  with 
absolute  alcohol,  filtered,  and  an  excess  of  ether  added.  The  amor- 
phous or,  after  a  longer  time,  crystalline  precipitate  consisting  of 
alkali-salts  of  the  biliary  acids  is  used  in  performing  Petten- 
kofer's  test. 

Bile-coloring  matters  occur  in  the  urine  in  dificront  forms  of 
icterus.  A  urine  containing  bile-coloring  matters  13  always  abnor- 
mally colored — yellow,  yellowish  brown,  deep  brown,  greenish  yellow, 
greenish  brown,  or  nearly  pure  green.  On  shaking  it  froths,  and 
the  bubbles  are  yellow  or  yellowish  green  in  color.  As  a  rule  icteric 
urine  is  somewhat  cloudy,  and  the  sediment  is  frequently,  especially 
when  it  contains  epithelium-cells,  rather  strongly  colored  by  the 
bile-coloring  matters.  In  regard  to  the  occurrence  of  urobilin  in 
icteric  urine  see  page  371. 

Detection  of  Bile-coloring  Matters  in  urine.  Many  tests  have 
"been  proposed  for  the  detection  of  bile-coloring  matters.  Ordina- 
rily we  obtain  the  best  results  either  with  Gmeliu's  or  with  Hup- 
pert's  test. 

Gmelin's  test  may  be  applied  directly  to  the  urine;  but  it  is 
better  to  use  Eosenbach's  modification.  "  Filter  the  urine,  which 
is  deep-colored  from  the  retaiued  epithelium-cells  and  bodies  of  that 
kind,  through  a  very  small  filter.  After  the  liquid  has  entirely 
passed  through  apply  to  the  inside  of  the  filter  a  drop  of  nitric  acid 
which  contains  only  very  little  nitrous  acid.  A  pale-yellow  spot  will 
be  formed  which  is  surrounded  by  colored  rings  which  appear  yellow- 
ish red,  violet,  blue,  and  green.  This  modification  is  very  delicate, 
and  it  is  hardly  possible  to  mistake  indican  and  other  coloring  mat- 
ters for  the  bile-pigments.  Several  other  modifications  of  Gmelin's 
test  on  the  urine  directly,  as  with  concentrated  sulphuric  acid  and 
nitrate,  etc.,  have  been  proposed,  but  they  are  neither  simpler  nor 
more  accurate  than  Rosenbach's  modification. 

Huppert's  Reqctioj]^  In  a  dark-colored  urine  or  one  rich  in 
indican  we  do  not  always  obtain  good  results  with  Gmelin's  test. 
In  such  cases,  as  also  in  urines  containing  blood -coloring  matters 
at  the  same  time,  the  urine  is  treated  with  lime-water,  or  first  with 
someCaClg  solution,  and  then  with  a  solution  of  soda  or  ammonium 
carbonate.  The  precipitate  which  contains  the  bile-coloring  mat- 
ters is  filtered  and  used  for  Huppert's  test  (see  page  154). 

The  precipitate  consisting  of  lime-pigments  may  also  be  shaken 
out  with  chloroform  after  washing  in  water  and  after  bemg  acidified 
with  acetic  acid.  The  bilirubin  is  taken  up  by  the  chloroform, 
which  is  colored  yellow  thereby,  while  the  acetic  acid  solution  is 
colored  green  by  the  bilirubin.     Both  solutions  may  then  be  used 


406  PHYSIOLOGICAL  CHEMISTRY. 

for  Gmelin's  test  (HoppE-SETLER),and  small  amounts  of  bile-color- 
ing matters  may  be  detected  in  this  way.  The  lime-pigm^ts  may, 
according  to  Hilger,  also  be  used  directly  for  Gmelin^s  test  in  the 
following  way  :  Spread  them  on  a  porcelain  dish  in  a  thin  layer, 
and  add  carefully  a  drop  of  nitric  acid.  The  reaction  generally 
appeals  very  beautiful. 

Stok_yxs!.s  re«c^^o?^  is  especially  valuable  in  those  cases  in  which 
the  urine  contains  only  very  little  bile-coloring  matter  together  with 
larger  amounts  of  other  coloring  matters.  The  test  is  performed 
as  follows  :  20-30  c.  c.  urine  are  treated  with  5-10  c.  c.  of  a  solu- 
tion of  zinc  acetate  (1  :  5).  The  precipitate  is  washed  on  a  small 
filter  with  water  and  then  dissolved  in  a  little  ammonia.  The  new 
filtrate  gives,  directly  or  after  it  has  stood  a  short  time  in  the  air 
until  it  has  a  peculiar  brownish-green  color,  the  absorption-bands 
of  bilicyanin  (see  page  155).  4. 

Many  other  reactions  for  bile-coloring  matters  in  the  urine  have 
been  proposed;  but  as  the  above-mentioned  are  sufiicient,  it  is  per- 
haps only  necessary  to  give  here  a  few  of  the  other  reactions  with- 
out entering  into  details. 

Ultzmann's  reaction  consists  in  treating  about  10  c.  c.  of  the  urine  with 
3-4  c.  c.  concentrated  caustic-potash  solution  and  then  acidifying  with  hydro- 
chloric acid.     The  urine  will  become  a  beautiful  green. 

SM3TH's_,;R^ac<^■o^i.  Pour  carefully  over  the  urine  tincture  of  iodine,  whereby 
a  green  ring  appears  between  the  two  liquids.  You  may  also  shake  the  urine 
with  tincture  of  iodine  until  it  has  a  green  color. 

Ehrlich's  Test.  First  mix  the  urine  with  an  equal  volume  of  dilute  acetic 
acid  and  then  add  drop  by  drop  a  solution  of  sulpho-diazobenzol.  The  acid 
mixture  becomes  dark  red  in  the  presence  of  bilirubin,  and  this  color  becomes 
bluish  violet  on  the  addition  of  glacial  acetic  acid.  The  sulpho-diazobenzol 
is  prepared  with  1  grm.  sulphanilic  acid,  15  c.  c.  hydrochloric  acid,  and  0.1 
grm.  sodium  nitrite  ;  this  solution  is  diluted  to  1  litre  with  water. 

Medicinal  coloring  matters  produced  from  santonin,  rhubarb,  senna, 
etc. ,  may  give  an  abnormal  color  to  the  urine,  which  may  be  mistaken  for  the 
bile-coloring  matters,  or  in  alkaline  urines  perhaps  for  blood-coloring  matters. 
If  hydrochloric  acid  is  added  to  such  a  urine,  it  becomes  yellow  or  pale  yellow, 
while  on  the  addition  of  an  excess  of  alkali  it  becomes  more  or  less  beautifully 
red. 

Sugar  in  Urine. 

Grape-sugar,  CgHijOg,  also  called  glucose,  dextrose,  and 
diabetic  sugar,  occurs  chiefly  in  the  vegetable  kingdom;  but  it  is 
found  in  very  small  amounts  in  the  blood,  on  an  average  of  1.5  p.  m., 
and  also  as  traces  in  other  animal  fluids  and  organs.  The  occurrence 
of  traces  of  grape-sugar  in  the  urine  of  perfectly  healthy  persons 
can  hardly  be  disputed.     If  sugar  appears  in  the  urine  in  constant 


THE   URINE.  407 

and  in  specially  large  amounts,  it  must  be  considered  as  an  abnor- 
mal constituent. 

Small  amounts  of  glucose  may  pass  into  the  urine  from  an  ex- 
cessive supply  of  sugar  when  the  body,  by  absorption  from  the 
intestines,  takes  up  more  sugar  than  it  can  assimilate  (Worm 
Muller;  F.  Hofmeister,  De  Joxg).  Also  after  starchy  food 
HoFMEiSTER  observed  iu  dogs,  whose  power  of  assimilating  sugar 
had  been  greatly  reduced  by  the  almost  complete  withdrawal  of 
food  for  several  days,  that  glycosuria  appeared  (starvation-dia- 
betes according  to  Hofmeister).  Iu  man  the  appearance  of 
glucose  in  the  urine  has  been  observed  in  numerous  and  various 
pathological  conditions,  such  as  lesions  of  the  brain  and  especially 
of  the  medulla  oblongata,  abnormal  circulation  in  the  abdomen, 
heart  and  lung  diseases,  cirrhosis  of  the  liver,  cholera,  etc.,  etc. 
Glycosuria  has  also  been  produced  iu  animals  in  various  ways,  as 
by  puncture  of  the  fourth  ventricle  (piqure),  cutting  through  the 
spinal  marrow,  irritation  of  the  pneumogastric  nerve,  poisoning 
with  carbon  monoxide,  curare,  amyl-nitrite,  o-nitro-phenyl-propiolic 
acid,  phloridzin,  and  many  other  substances,  also  by  the  injection 
of  dilute  common-salt  solution  into  the  blood-vessels,  and  in  many 
other  ways.  The  observation  of  v.  Merixg  and  Minkowski  that 
in  dogs  after  total  extirpation  of  the  pancreas  a  very  copious  and 
continuous  secretion  of  sugar,  a  true  diabetes,  appears  is  of  special 
interest. 

The  continuous  appearance  of  sugar  in  human  urine,  sometimes 
in  very  considerable  am.ounts,  occurs  in  diabetes  mellitus.  In 
this  disease  there  may  be  an  elimination  of  1  kilogramme  of  grape- 
sugar  during  the  24  hours,  or  even  more.  In  the  beginning  of  the 
disease,  when  the  quantity  of  sugar  is  still  very  small,  the  urine 
often  does  not  appear  abnormal.  In  more  developed,  typical  cases 
the  quantity  of  urine  voided  increases  considerably  to  3-6-10  litres 
per  24  hours.  The  percentage  of  the  physiological  constituents  is 
as  a  rule  very  low,  while  their  absolute  daily  quantity  is  increased. 
The  urine  is  pale,  but  of  a  high  specific  gravity,  1.030-1.040  or 
even  higher.  The  high  specific  gravity  depends  upon  the  sugar 
present,  which  varies  in  different  cases,  but  may  even  amount  to 
10^.     The  urine  is  therefore  characterized  in  typical  cases  of  dia- 


408  PHTSIOLOOICAL   CHEMISTBT. 

betes  by  the  very  large  quantity  voided,  by  the  pale  color  and  high 
specific  gravity,  and  by  its  containing  sugar. 

That  the  urine  after  the  introduction  of  certain  medicines  or 
poisonous  bodies  into  the  system  contains  reducing  bodies,  paired  • 
glycuronic  acids,  which  may  be  mistaken  for  sugar,  has  been  men- 
tioned in  the  previous  pages. 

Properties  of  Grape-sugar.  Grape-sugar  crystallizes  sometimes 
with  1  mol.  water  of  crystallization  in  warty  masses  or  small  leaves 
or  plates,  and  sometimes  when  free  from  water  in  needles.  The 
sugar  containing  water  of  crystallization  melts  even  below  100°  C. 
and  loses  its  water  of  crystallization  at  110°  C.  The  anhydrous 
sugar  melts  at  146°  C.  and  is  converted  into  glucosan,  CgHioOs,  at 
170°  C.  with  the  elimination  of  water.  On  strongly  heating  it  is 
converted  into  caramel  and  then  decomposed. 

Grape-sugar  is  readily  soluble  in  water.  This  solution,  which 
is  not  as  sweet  as  a  cane-sugar  solution  of  the  same  strength,  is 
dextro-gyrate.  The  specific  rotary  power  of  a  watery  solution  of 
l-15fo  anhydrous  glucose  at  -|-  20°  C.  is  indeed  somewhat  variable, 
52.52°-52.9°  (Landolt),  but  the  average  may  be  considered  as 
-{-  52.6°.  Anhydrous  glucose  dissolves  sparingly  in  cold,  but  more 
freely  in  boiling,  alcohol.  100  parts  85^  alcohol  dissolves  1.94 
parts  glucose  at  +  17.5°  0.  and  21.7  parts  at  the  boiling  tempera- 
ture (AiSTTHOisr).  Glucose  is  insoluble  in  ether.  If  an  alcoholic 
caustic-alkali  solution  is  added  to  an  alcoholic  solution  of  glucose? 
an  amorj)hous  precipitate  of  insoluble  saccharate  is  formed.  On 
warming  the  saccharate  decomposes  easily  with  the  formation  of  a 
yellow  or  brownish  color  which  is  the  basis  of  the  following  re- 
action. 

Moore's  Test.  If  a  glucose  solution  is  treated  with  about  i  of 
its  volume  of  caustic  potash  or  soda  and  warmed,  the  solution  be- 
comes first  yellow,  then  orange,  yellowish  brown,  and  lastly  dark 
brown.  It  has  at  the  same  time  a  faint  odor  of  caramel,  and  this 
odor  is  more  pronounced  on  acidification. 

Glucose  forms  many  crystallizable  combinations  with  NaCl,  of 
which  the  easiest  to  obtain  is  (06Hi206)2-NaCl  +  H2O,  which  forms 
large  colorless  six-sided  double  pyramids  or  rhomboids  with  13.40,^ 
NaCl. 

Glucose   in  neutral   or  very  faintly-acid  (by  an  organic  acid) 


THE   URINE.  409 

solution  passes  into  alcoholic  fermentation  with  beer -yeast, 
C'eHiaOg  —  BCjHs.OH  +  2CO2.  The  most  favorable  temperature 
for  this  fermentation  is  about  35°  C.  Besides  the  alcohol  and 
carbon  dioxide  there  are  formed,  especially  at  higher  temperatures, 
small  quantities  of  homologous  alcohols  (amyl-alcohol),  glycerin,  and 
succinic  acid.  In  the  presence  of  acid  milk  or  cheese  the  grape- 
sugar  passes,  especially  in  the  presence  of  a  base  such  as  ZnO  or 
CaCOs,  into  lactic-acid  fermentation:  CeHijOs  =  2C3H6O3.  (This 
process  is  even  more  complicated  and  CO2  is  formed  thereby,  Bou- 
TRON,  HuEPPE.)  The  lactic  acid  may  then  pass  into  butyric  acid- 
fermentation  :  2C3H6O3  =  C^HsOj  +  3CO2  +  4H. 

Grape-sugar  reduces  several  metallic  oxides,  such  as  copper 
oxide,  bismuth  oxide,  mercuric  oxide,  in  alkaline  solutions,  and  the 
most  important  reactions  for  sugar  are  based  on  this  fact. 

Trommer's  test  is  based  on  the  property  that  glucose  possesses 
of  reducing  copper-hydrated  oxide  in  alkaline  solution  into  sub- 
oxide. Treat  the  glucose  solution  with  about  \-\  vol.  caustic 
soda  and  then  carefully  add  a  dilute  copper-sulphate  solution. 
The  copper-hydrated  oxide  is  thereby  dissolved,  forming  a  beautiful 
blue  solution,  and  the  addition  of  copper  sulphate  is  continued 
until  a  very  small  amount  of  hydrate  remains  undissolved  in  the 
liquid.  This  is  now  warmed  and  a  yellow  hydrated  suboxide  or 
red  suboxide  separates  even  below  the  boiling-point.  If  too  little 
copper  salt  has  been  added,  the  test  will  be  yellowish  brown  in  color 
as  in  Moore's  test;  but  if  an  excess  of  copper-salt  has  been  added, 
the  excess  of  hydrate  is  converted  on  boiling  into  a  dark-brown 
hydrate  poor  in  water  which  interferes  with  the  test.  To  prevent 
these  difficulties  the  so-called  FehlingJ^s  solution  may  be  em- 
ployed. This  reagent  is  obtained  by  mixing  before  use  equal 
volumes  of  an  alkaline  solution  of  Rochelle  salts  and  a  copper-sul- 
phate solution  (see  Quantitative  Estimation  of  Sugar  in  the  Urine  in 
regard  to  concentration).  This  solution  is  not  reduced  or  noticeably 
changed  by  boiling.  The  tartrate  holds  the  excess  of  copper- 
hydrate  oxide  in  solution,  and  an  excess  of  the  reagent  does  not 
interfere  in  the  performance  of  the  test.  In  the  presence  of  sugar 
this  solution  is  reduced. 

Bottger-Almen's  test  is  based  on  the  property  glucose  possesses 
of  reducing  bismuth  oxide  in  alkaline  solution.     The  reagent  best 


410  PHYSIOLOGICAL  CHEMISTRY. 

adapted  for  this  purpose  is  obtained,  according  to  Nylaxder's 
modification  of  ALME]!f's  original  test,  by  dissolving  4  grms. 
Roclielle  salt  in  100  parts  caustic  soda  of  lOfo  NaHO  and  adding 
2  gnns.  bismuth  subnitrate  and  digesting  on  the  water-bath  until 
as  much  of  the  bismuth  salt  is  dissolved  as  possible.  If  a  glucose 
solution  is  treated  with  about  J^-  vol.,  or  with  a  larger  quantity  of 
the  solution  when  large  quantities  of  sugar  are  present,  and  boiled 
for  a  few  minutes,  the  solution  becomes  first  yellow,  then  yellowish 
brown,  and  lastly  nearly  black,  and  after  a  time  a  black  deposit  of 
bismuth  (?)  settles. 

On  heating  with  phentlhtdrazix  a  grape-sugar  solution 
gives  a  precipitate  consisting  of  fine  yellow  crystalline  needles 
which  are  nearly  insoluble  in  water  but  soluble  in  boiling  alcohol, 
and  which  separate  again  on  treating  the  alcoholic  solution  with 
water.  The  crystalline  precipitate  consists  of  ]}lienylglucosazoiie 
(E.  Fischer)  :  Q.^^Q),  +  2C6H5.X2H3  =  CigH^aNA  +  SH^O  +  2H. 
This  compound  melts  when  pure  at  204°-205°  C. 

Glucose  is  not  precipitated  by  a  lead-acetate  solution,  but  is 
almost  completely  precipitated  by  an  ammoniacal  basic  lead-acetate 
solution.  On  warming  the  precipitate  becomes  flesh-color  or  rose- 
red. 

If  a  watery  solution  of  grape-sugar  is  treated  with  BEifzoYL- 
CHLORiDE  and  an  excess  of  caustic  soda  and  shaken  until  the  odor 
of  benzoylchloride  has  disappeared,  a  precipitate  of  benzoic-acid 
ester  of  glycose  will  be  produced  which  is  insoluble  in  water  or 
alkali  (Baumai^x). 

If  \-\.  c.  c.  of  a  dilute  watery  solution  of  glucose  is  treated  with 

a  few  drops  of  a  15^  alcoholic  solution  of  a-naphthol,  the  liquid  is 

colored  a  beautiful  violet  on  the  addition  of  1-2  c.  c.  concentrated 

sulphuric  acid  (Molisch).     This  reaction  depends  on  the  formation 

of  furfurol  from  the  sugar  by  the  action  of  the  sulphuric  acid. 

DiAZOBENZOii-suLPHONic  ACID  gives  with  a  sugar  solutioa  made  alkaline 
with  a  fixed  alkali  a  red  color  gradually  cliauging  after  10-15  minutes 
to  violet  (Penzoldt  and  Fischer).  Orthonitrophenyl-propiolic  acid 
j-ields  indigo  when  boiled  with  a  small  quantity  of  sugar  and  sodium  car- 
bonate, and  this  is  converted  into  indigo-white  by  an  excess  of  sugar  (Baeter). 
An  alkaline  solution  of  grape-sugar  is  colored  deep  red  on  being  warmed  with 
a  dilute  solution  of  picric  acid  (Brann). 

The  detection  of  sugar  in  urine  is  ordinarily,  in  the  presence  of 
not  too  little   sugar,  a  very  simple  opperation.     The  presence  of 


THE   URINE.  411 

only  very  small  amounts  may  make  its  detection  sometimes  very 
difficult  and  laborious.  A  urine  containing  albumin  must  first 
have  the  albumin  removed  by  coagulation  with  acetic  acid  and  heat 
before  it  can  be  tested  for  sugar. 

The  tests  which  are  most  frequently  employed  and  are  especially 
recommended  are  as  follows: 

Trommer's  test.  In  a  typical  diabetic  urine  or  one  rich  in 
sugar  this  test  succeeds  well,  and  it  may  be  performed  in  the 
manner  suggested  on  page  409.  This  test  may  lead  to  very  great 
mistakes  in  urines  poor  in  sugar,  especially  when  they  have  at  the 
same  time  normal  or  increased  amounts  of  physiological  constitu- 
ents, and  therefore  it  cannot  be  recommended  to  physicians  or  to 
persons  little  practised  in  such  work.  Normal  urine  contains 
reducible  substances,  such  as  uric  acid,  creatinin,  and  others,  and 
therefore  a  reduction  takes  place  with  all  urine  on  using  this  test. 
We  generally  do  not  have  a  separation  of  copper  suboxide,  but  still 
if  we  vary  the  proportion  of  the  alkali  to  the  copper  sulphate  and 
boil,  we  often  have  an  actual  separation  of  suboxide  in  normal 
urines,  or  we  obtain  a  peculiar  yellowish-red  liquid  due  to  finely- 
divided  hydrated  suboxide.  This  occurs  especially  on  the  addition 
of  much  alkali  or  too  much  copper  sulphate,  and  by  careless  ma- 
nipulation the  inexjierieuced  worker  may  therefore  sometimes 
obtain  apparently  positive  results  in  a  normal  urine.  Also  as  urine 
contains  substances  such  as  creatinin  and  ammonia  (from  the 
urea),  which  in  the  presence  of  only  little  sugar  may  keep  the  cop- 
per suboxide  in  solution,  therefore  in  inexperienced  hands  small 
amounts  of  sugar  may  be  overlooked. 

Trommer's  test  may  indeed  be  made  positive  and  useful,  even  in 
the  presence  of  very  small  amounts  of  sugar,  by  using  the  modifica- 
tion suggested  by  Worm  Muller.  As  this  modification  is  rather 
complicated,  and  besides  this  requires  much  practice  and  exactness, 
it  is  probably  rarely  employed  by  the  busy  physician.  The  follow- 
ing test  is  to  be  preferred  : 

Almen's  bismuth  test,  which  recently  has  been  incorrectly  called 
Nylander's  test,  is  performed  with  the  alkaline  bismuth  solution 
prepared  as  above  described  (page  410).  For  each  test  10  c.  c.  of 
urine  are  taken  and  treated  with  1  c.  c.  of  the  bismuth  solution  and 
boiled  for  a  few  minutes.  In  the  presence  of  sugar  the  urine 
becomes  darker  yellow  or  yellowish  brown.  Then  it  grows  darker, 
cloudy,  dark  brown,  or  nearly  black,  and  non-transparent.  After  a 
shorter  or  longer  time  a  black  deposit  appears,  the  supernatant 
liquid  gradually  clears,  but  still  remains  colored.  In  the  presence 
of  only  very  little  sugar  the  test  is  not  black  or  dark  brown,  but  is 
only  deeper-colored,  and  after  a  longer  time  we  only  see  on  the 
upper  layer  of  the  phosphate  precipitate  a  dark  or  black  edge  (of 
bismuth  ?).     In  the  presence  of  much  sugar  a  larger  amount  of 


412  PHYSIOLOGICAL  CHEMISTRY. 

reagent  may  be  used  without  disadvantage.  In  a  urine  poor  in 
sugar  we  must  only  use  1  c.  c.  of  the  reagent  for  every  10  c.  c.  of 
the  urine. 

This  test  shows  the  presence  of  1-0.5  p.  m.  sugar  in  the  urine. 
The  sources  of  error  which  interfere  in  Teommer's  test,  such  as  the 
presence  of  uric  acid  and  creatinin,  entirely  disappear  in  this 
test.  The  bismuth  test  is,  besides  this,  more  easily  performed,  and 
it  is  therefore  to  be  recommended  to  the  physician.  Small  amounts 
of  albumen  do  not  interfere  with  this  test;  large  amounts  may  give 
rise  to  an  error  by  forming  bismuth  sulphide,  and  therefore  must 
be  removed  by  coagulation. 

In  using  this  method  it  must  not  be  overlooked  that  it  is,  like 
Teommer's  test,  a  reduction  test,  and  it  consequently  may  show, 
besides  sugar,  certain  other  reducing  substances.  Such  bodies  are 
certain  coupled  glycuronic  acids  which  may  appear  in  the  urine. 
Salkowski  obtained  a  bluish-black  precipitate  with  this  reagent  in 
a  urine  after  the  use  of  rhubarb,  and  black  precipitates  have  been 
obtained  with  the  bismuth  test  after  the  use  of  turpentine  and  cer- 
tain other  medicines.  From  this  it  follows  that  we  should,  espe- 
cially when  the  reduction  is  not  very  great,  never  be  satisfied  with 
this  test  alone.  As  a  control  at  least  one  of  the  following  tests 
must  be  performed.  Among  these  the  fermentation  test  is  of 
special  value. 

Fermentation  Test.  On  using  this  test  we  must  proceed  in  vari- 
ous ways,  according  as  the  bismuth  test  gives  small  or  large  results. 
If  a  rather  strong  reduction  is  obtained,  the  urine  may  be  treated 
with  yeast  and  the  presence  of  sugar  determined  by  the  generation 
of  carbon  dioxide.  In  this  case  the  acid  urine,  or  otherwise  faintly 
acidified  with  tartaric  acid,  is  treated  with  yeast  which  has  previ- 
ously been  washed  by  decantation  with  water.  Pour  this  urine  to 
which  the  yeast  has  been  added  into  a  Scheottbr's  gas-burette,  or 
glass  tube  with  the  opeu  end  ground,  close  with  the  thumb,  and 
open  under  the  surface  of  mercury  contained  in  a  dish.  As  the 
fermentation  proceeds,  the  carbon  dioxide  collects  in  the  upper 
part  of  the  tube,  while  a  corresponding  quantity  of  liquid  is  expelled 
below.  As  a  control  in  this  case,  two  other  similar  tests  must  be 
made,  one  with  normal  urine  and  yeast  to  learn  the  amount  of  gas 
usually  developed,  and  the  other  with  a  sugar  solution  and  yeast  to 
determine  the  activity  of  the  yeast. 

If,  on  the  contrary,  we  find  only  a  faint  reduction  with  the  bis- 
muth test,  no  positive  conclusion  can  be  drawn  from  the  absence  of 
any  carbon  dioxide  or  the  appearance  of  a  very  insignificant 
amount.  In  this  case  proceed  in  the  following  way  :  Treat  the 
acid  urine,  or  the  urine  which  has  been  faintly  acidified  with  tar- 
taric acid,  with  yeast  whose  activity  has  been  tested  by  a  special 
test  on  a  sugar  solution,  and  allow  it  to  stand  24-48  hours  at  the 


TEE  URINE.  413 

temperature  of  the  room,  or,  better,  at  a  little  higher  temperature. 
After  this  time  test  again  with  the  bismuth  test,  and  if  the  reac- 
tion now  gives  negative  results,  then  sugar  was  previously  present. 
But  if  the  reaction  continues  to  give  positive  results,  then  it  shows 
— if  the  yeast  is  active — the  presence  of  other  reducing,  ferment- 
able bodies.  There  may  indeed  be  a  possibility  that  the  urine  also 
contains  some  sugar  besides  these  bodies.  This  possibility  is  decided 
by  the  following  test  : 

Phenylhydrazin  Test.  According  to  v.  Jaksch,  this  test  is  per- 
formed in  the  following  way  :  Add  in  a  test-tube  containing  8-10 
c.  c.  of  the  urine  two  knife-points  of  phenylhydrazin  hydrochloride 
and  three  knife-points  sodium  acetate,  and  when  the  added  salts 
do  not  dissolve  on  warming  add  more  water.  The  mixture  is  heated 
in  boiling  water  and  kept  there  for  one  hour  to  avoid  a  confusion 
with  phenylhydrazin-glycuronic  acid  (v.  Jaksch  and  Hikschl). 
It  is  then  poured  into  a  beaker  of  cold  water.  If  the  quantity  of 
sugar  present  is  not  too  small,  a  yellow  crystalline  precipitate  is  now 
obtained.  If  the  precipitate  appears  amorphous,  then  on  looking 
at  it  under  the  microscope  it  appears  partly  as  single  and  partly 
as  groups  of  yellow  needles.  If  very  little  sugar  is  present,  pour 
the  test  into  a  conical  glass  and  examine  the  sediment.  In  this 
case  at  least  a  few  phenylglucosazone  crystals  are  found,  while 
the  occurrence  of  smaller  and  larger  yellow  plates  or  highly-refrac- 
tive brown  globules  do  not  show  the  presence  of  sugar.  Accord- 
ing to  V.  Jaksch,  this  reaction  is  very  reliable,  and  by  it  the 
presence  of  0.3  p.  m.  sugar  can  be  detected  (Rosenberg,  Geter). 
A  confounding  with  glycuronic  acid  is,  according  to  Hirschl,  not 
to  be  apprehended  when  it  is  not  heated  in  the  water-bath  for  too 
short  a  time  (one  hour).  In  doubtful  cases  where  we  wish  to  be 
quite  sure,  prepare  the  crystals  from  a  large  quantity  of  urine,  dis- 
solve them  on  the  filter  by  pouring  over  them  hot  alcohol,  treat  the 
filtrate  with  water,  and  boil  off  the  alcohol.  If  the  characteristic 
yellow  crystalline  needles,  whose  melting-point  (204°-205°  C.)  is 
also  determined,  are  now  obtained,  then  this  test  is  quite  decisive. 

Polarization.  The  polariscopic  investigation  is  of  great  value, 
especially  as  in  many  cases  it  quickly  differentiates  between  sugar 
and  other  reducible,  often  laevo-gyrate  substances.  In  the  presence 
of  only  very  little  sugar  the  value  of  this  test  depends  on  the  delicacy 
of  the  instrument  and  the  dexterity  of  the  observer;  therefore  this 
method  is  perhaps  inferior  in  most  cases  to  the  bismuth  test  or  to 
the  phenylhydrazin  test. 

If  small  quantities  of  sugar  are  to  be  isolated  from  the  urine, 
precipitate  the  urine  first  with  sugar  of  lead,  filter,  precipitate  the 
filtrate  with  ammoniacal  lead  acetate,  wash  this  precipitate  with 
water,  decompose  it  with  HgS  when  suspended  in  water,  concentrate 
the  filtrate,  treat  it  with  strong  alcohol  until  it  is  80  vol.  per  cent,  filter 


414  PHYSIOLOGICAL  CHEMISTRY. 

wheu  necessary,  and  add  an  alcoholic  caustic-alkali  solution.  Dis- 
solve the  precipitate  consisting  of  saccharates  in  a  little  water,  pre- 
cipitate the  potash  by  an  excess  of  tartaric  acid,  neutralize  tlie  fil- 
trate with  calcium  carbonate  in  the  cold,  and  filter.  The  filtrate 
may  be  used  for  testing  with  the  polariscope  as  well  as  in  the  fer- 
mentation, bismuth,  and  phenylhydrazin  tests.  The  presence  of 
grape-sugar  may  be  detected  by  this  same  process  in  animal  fluids 
or  tissues,  from  which  the  albumins  have  first  been  removed  by 
coagulation  or  by  the  addition  of  alcohol. 

For  the  physician,  who  naturally  wants  specially  simple  and 
quick  methods,  the  bismuth  test  must  be  especially  recommended, 
as  this  may  be  controlled  when  necessary  by  the  fermentation  or 
phenylhydrazin  test. 

Other  tests  for  sugar,  as,  for  example,  the  reaction  with  orthonitropbenyl- 
propiolic  acid,  picric  acid,  diazobenzol  sulphonic  acid,  are  superfluous.  The 
reaciiou  with  a-naphthol,  which  is  a  reaction  for  carbohydrates  in  general,  for 
gljcui-ouic  acid  and  mucin,  may,  because  of  its  extreme  delicacy,  give  rise  to 
mistakes,  and  is  therefore  not  to  be  recommended  to  physicians. 

Quantitative  Estimation  of  Svgar  in  the  urine.  The  urine  for 
such  an  estimation  must  first  be  tested  for  albumin,  and  if  any  be 
present  it  niust  be  removed  by  coagulation  and  the  addition  of 
acetic  acid,  care  being  taken  not  to  increase  or  diminish  the  original 
volume  of  urine.  The  quantity  of  sugar  may  be  determined  by 
TiTEATiON"  with  Eehling's  or  KiSTAPP's  solution,  by  permenta- 
Tioiir  or  by  polarization. 

The  titration  liquids  not  only  react  with  sugar,  but  also  with 
certain  other  reducing  substances,  and  on  this  account  the  titration 
methods  give  rather  high  results.  When  large  quantities  of  sugar 
are  present,  as  in  typical  diabetic  urine,  which  generally  contains  a 
lower  percentage  of  normal  reducing  constituents,  this  is  indeed 
of  little  account;  but  when  small  amounts  of  sugar  are  present  in 
an  otherwise  normal  urine,  the  mistake  may,  on  the  contrary,  be 
important,  as  the  reducing  power  of  normal  urine  may  correspond 
to  4  p.  m.  grape-sugar  (see  page  374).  In  such  cases  the  titration 
method  must  be  employed  in  connection  with  the  fermentation 
method,  which  will  be  described  later.  It  is  to  be  remarked  that 
in  typical  diabetic  urines  with  considerable  amounts  of  sugar  the 
titration  with  Fehling's  solution  is  just  as  reliable  as  with  Knapp^s 
solution.  When  the  urine,  on  the  contrary,  contains  only  little 
sugar  with  normal  amounts  of  physiological  constituents,  then  the 
titration  with  Feeling's  solution  is  more  diflQcult,  indeed  in  cer- 
tain cases  almost  impossible,  the  results  being  very  uncertain.  In 
such  cases  Knapp's  method  gives  good  results,  according  to  Worm 
MuLLER  and  his  pupils. 

The  titration  with  Feeling's  solution  depends  on  the  power 
of  sugar  to  reduce  copper  oxide  in  alkaline  solutions.     For  this  we 


THE  URINE.  415 

formerly  employed  a  solution  which  contained  a  mixture  of  copper 
sulphate,  Rochelle  salt,  and  sodium  or  potassium  hydrate  (Feh- 
lixg's  solution) ;  but  as  such  a  solution  readily  changes,  we  now 
prepare  a  copper-sulphate  solution  and  an  alkaline  Kochelle-salt 
solution  separately,  and  mix  equal  volumes  of  the  two  solutions 
before  using. 

The  concentration  of  the  copper-sulpliate  solution  is  such  that 
10  c.  c.  of  this  solution  is  reduced  by  0.05  grm.  grape-sugar.  The 
copper-sulphate  solution  contains  34.65  grms.  pure,  crystallized,  non- 
effloi-escent  copper  sulphate  in  1  litre.  The  sulphate  is  crystallized 
from  a  hot  saturated  solution  by  cooling  and  stirring;  and  the 
crystals  are  separated  from  the  mother-liquor  and  pressed  between 
blotting-paper  until  dry.  'J'he  Rochelle-salt  solution  is  prepared 
by  dissolving  1T3  grms.  of  the  salt  in  350  c.  c.  water,  adding  600 
c.  c.  of  a  caustic-soda  solution  of  a  sjjecific  gravity  of  1.12,  and  dilut- 
ing with  water  to  1  litre.  According  to  Worm  Muller,  these 
three  liquids — Rochelle-salt  solution,  caustic  soda,  and  water — 
should  be  separately  boiled  before  mixing  together.  For  each 
titration  mix  in  a  small  flask  or  porcelain  dish  exactly  10  c.  c.  of 
the  copper-sulphate  solution  and  10  c.  c,  of  the  alkaline  Eochelle- 
salt  solution  and  add  30  c.  c.  water. 

The  urine  free  from  albumin  is  diluted  before  the  titration 
with  water  so  that  10  c.  c.  of  the  copper  solution  requires  between 
5  and  10  c.  c.  of  the  diluted  urine,  which  corresponds  to  between 
1  and  ^i)  sugar.  A  urine  of  a  specific  gravity  of  1.030  may  be 
diluted  five  times;  one  more  concentrated,  ten  times.  The  urine 
so  diluted  is  poured  into  a  burette  and  allowed  to  flow  into  the 
boiling  copper-sulphate  and  Eochelle-salt  solution  until  the  copper 
oxide  is  completely  reduced.  This  has  taken  place  when,  after 
boiling,  tlie  blue  color  of  the  solution  disappears.  It  is  very  dif- 
ficult and  requires  some  practice  to  exactly  determine  this  point, 
especially  when  the  copper  suboxide  settles  with  difficulty.  To 
determine  whether  the  color  has  disappeared,  allow  the  copper 
suboxide  to  settle  a  little  below  the  meniscus  formed  by  the  surface 
of  the  liquid.  If  this  layer  is  not  blue,  the  operation  is  repeated, 
addii]g  0.1  c.  c.  less  of  urine;  and  if,  after  the  copper  suboxide  has 
settled,  the  liquid  has  a  blue  color,  the  titration  may  be  considered 
as  completed.  Because  of  the  difiiculty  in  obtaining  this  point 
exactly  another  end-reaction  has  been  suggested.  This  consists  in 
filtering  immediately  after  boiling  a  small  portion  of  the  treated 
urine  through  a  small  filter  into  a  test-tube  which  contains  a  little 
acetic  acid  and  a  few  drops  of  potassium-ferrocyanide  solution  and 
water.  The  smallest  quantity  of  copper  is  shown  by  a  red  colora- 
tion. If  the  operation  is  quickly  conducted  so  that  no  oxidation 
of  the  suboxide  into  oxide  takes  place,  this  end-reaction  is  of  value 
for  urines  which  are  rich  in  sugar  and  poor  in  urea  and  which 


416  PHTSIOLOGICAL   CHEMISTRY. 

have  been  strongly  diluted  with  water.  In  urines  poor  in  sugar 
which  contain  the  normal  amount  of  urea  and  which  have  not  been 
strongly  diluted,  a  rather  abundant  formation  of  ammonia  from 
the  urea  may  take  place  on  boiling  the  alkaline  liquid.  This  am- 
monia dissolves  the  suboxide  in  part,  which  easily  passes  into  oxide 
thereby,  and  besides  this  the  dissolved  suboxide  gives  a  red  color 
with  potassium  ferrocyanide.  In  just  those  cases  in  which  the 
titration  is  most  difficult  this  end-reaction  is  the  least  reliable. 
Practice  also  renders  it  unnecessary,  and  it  is  therefore  best  to 
depend  simply  upon  the  appearance  of  the  liquid. 

To  facilitate  the  settling  of  the  copper  suboxide  and  thereby 
clearing  the  liquid,  MuNK  has  lately  suggested  the  addition  of  a 
little  calcium-chloride  solution  and  boiling  again.  A  precipitate  of 
calcium  tartrate  is  produced  which  carries  down  the  suspended 
copper  suboxide  with  it,  and  the  color  of  the  liquid  can  then  be 
better  seen.  This  artifice  succeeds  in  many  cases,  but  unfortunately 
there  are  urines  in  which  the  titration  with  Feeling's  solution  in 
no  way  gives  exact  results. 

The  necessary  conditions  for  the  success  of  the  titration  under 
all  circumstances  are,  according  to  Soxhlet,  the  following:  The 
copper-sulphate  and  Rochelle-salt  solution  must,  as  above,  be  diluted 
to  50  c.  c.  with  water;  the  urine  must  only  contain  between  0.5^ 
and  Ifo  sugar,  and  the  total  quantity  of  urine  required  for  the  re- 
duction must  be  added  to  the  titration  liquid  at  once  and  boiled 
with  it.  Erom  this  last  condition  it  follows  that  the  titration  is 
dependent  upon  minute  details,  and  several  titrations  are  required 
for  each  determination. 

It  is  best  to  give  here  directions  for  the  titration.  The  proper 
amount  of  copper-sulphate  and  Kochelle-salt  solution  and  water 
(total  volume  =  50  c.  c.)  is  heated  to  boiling  in  a  flask:  the  color 
must  remain  blue.  The  urine  diluted  five  times  is  now  added  to 
the  boiling-hot  liquid,  1  c.  c.  at  a  time;  after  each  addition  of 
urine  boil  for  a  few  seconds,  and  look  for  the  appearance  of  the 
end-reaction.  If  you  find,  for  example,  that  3  c.  c.  is  too  little  but 
that  4  c.  c.  is  too  much  (the  liquid  becoming  yellowish),  then  the 
urine  has  not  been  sufficiently  diluted,  for  it  should  require  be- 
tween 5  and  10  c.  c.  of  the  urine  to  produce  the  complete  reduc- 
tion. The  urine  is  now  diluted  ten  times,  and  it  should  now 
require  between  6  and  8  c.  c.  for  a  total  reduction.  Now  prepare 
four  new  tests,  which  are  boiled  simultaneously  to  save  time,  and 
add  at  one  time  respectively  6,  ^,  7,  and  7|-  c.  c.  of  urine.  If  it  is 
found  that  between  6|  and  7  c.  c.  are  necessary  to  produce  the 
end-reaction,  then  make  four  other  tests,  to  which  add  respectively 
6.6,  6.7,6.8,  and  6.9  c.  c.  of  urine.  If  in  this  case  the  liquid  i3 
still  somewhat  bluish  with  6.7  c.  c.  and  completely  decolorized  with 
6.8  c.  c,  we  then  consider  the  average  figure  6.75  c.  c.  as  correct. 


THE   URINE.  417 

The  calculation  is  simple.  The  6.75  c.  c.  used  contain  0.05  grm. 
sugar,  and  the  percentage  of  sugar  in  the  dilute  urine  is  therefore 

(6.75  :  0.05  =z  100  :  cc)  =  ^  =  0.74.     But    as    the    urine   was 

0.7a 

diluted  with  ten  times  its  volume  of  water,  the  undiluted  urine 

5  X  10 
contained  — ^^v-  =  7.4^.     The  general  formula  on  using  10  c.  c. 

5  X  w 
copper-sulphate  solution  is  therefore  — t — ,  in  which  n  represents 

the  number  of  times  the  urine  has  been  diluted  and  k  the  number 
of  c.  c.  used  for  the  titration  of  the  diluted  urine. 

The  TITRATION  ACCORDING  TO  Knapp  depends  on  the  fact  that 
mercuric  cyanide  is  reduced  into  metallic  mercury  by  grape-sugar. 
The  titration  liquid  should  contain  10  grms.  chemically  pure  dry 
mercuric  cyanide  and  lUO  c.  c.  caustic-soda  solution  of  a  specitlc 
gravity  of  1.145  per  litre.  When  the  titration  is  performed  as 
described  below  (according  to  Worm  MiJLLER  and  Otto),  20  c.  c.  of 
this  solution  should  correspond  to  exactly  0.05  grm.  grape-sugar. 

Also  in  this  titration  the  quantity  of  sugar  in  the  urine  should 
be  between  l-^  and  l<fo,  and  here  also  the  extent  of  dilution  necessary 
must  be  determined  by  a  preliminary  test.  To  determine  the  end- 
reaction  as  described  below,  the  test  for  excess  of  mercury  is  made 
with  sulphuretted  hydrogen. 

In  performing  the  titration  allow  20  c.  c.  of  Knapp's  solution  to 
flow  into  a  flask  and  dilute  with  80  c.  c.  water,  or  when  you  have 
reason  to  think  that  the  urine  contains  less  than  0.5^  of  sugar,  then 
only  with  40-60  c.  c.  After  this  heat  to  boiling  and  allow  the 
dilute  urine  to  flow  gradually  into  the  hot  solution,  at  first  2  c,  c, 
then  1  c.  c,  then  0.5  c.  c,  then  0.2  c,  c,  and  lastly  0.1  c.  c.  After 
each  addition  let  it  boil  |  minute.  When  the  end-reaction  is 
approaching,  the  liquid  begins  to  clarify  and  the  mercury  separates 
with  the  phosphates.  The  end-reaction  is  determined  by  taking  a 
drop  of  the  upper  layer  of  the  liquid  into  a  capillary  tube  and  then 
blowing  it  out  on  pure  white  filter-paper.  The  moist  spot  is  first 
held  over  a  bottle  containing  fuming  hydrochloric  acid  and  then 
over  strong  sulphuretted  hydrogen.  The  presence  of  a  minimum 
quantity  of  mercury-salt  in  the  liquid  is  shown  by  the  spot  becom- 
ing yellowish,  which  is  seen  best  when  it  is  compared  with  a  second 
spot  which  has  not  been  exposed  to  sulphuretted  hydrogen.  The 
end-reaction  is  still  clearer  when  a  small  part  of  the  liquid  is 
filtered,  acidified  with  acetic  acid,  and  tested  with  sulphuretted 
hydrogen  (Otto).  The  calculations  are  just  as  simple  as  for  the 
previous  method. 

This  titration,  unlike  the  previous  one,  may  be  performed  not 
only  in  daylight,  but  also  in  artificial  light.     Knapp's  method  has 


418  PHYSIOLOGICAL  CHEMISTRY. 

the  following  advantages  over  Feeling's  method.  It  is  applicable 
even  when  the  quantity  of  sugar  in  the  urine  is  very  small  and  the 
amount  of  the  other  urinary  constituents  is  normal.  It  is  more 
easily  performed,  and  the  titration  liquids  may  be  kept  without 
decomposing  for  a  long  time  (Woem  MiJLLEEand.  his  pupils).  The 
views  of  different  investigators  on  the  value  of  this  titration  method 
are  still  somewhat  contradictory. 

Estimation  of  the  Quantity  of  Sugar  by  Fermentation. 
This  may  be  done  in  various  ways  ;  the  simplest,  and  at  the  same 
time  sufficiently  exact  for  ordinary  cases,  is  Koberts'  method. 
This  method  consists  in  determining  the  specific  gravity  of  the 
urine  before  and  after  fermentation.  In  the  fermentation  of  sugar, 
carbon  dioxide  and  alcohol  are  formed  as  chief  products  and  the 
specific  gravity  is  lowered,  partly  on  account  of  the  disappearance 
of  the  sugar  and  partly  on  account  of  the  production  of  alcohol. 
Eoberts  found,  and  this  has  been  substantiated  later  by  several 
other  investigators  (Worm  Mtjller  and  others),  that  a  decrease  of 
0.001  in  the  specific  gravity  corresponded  to  0.23^  sugar.  If  the 
urine,  for  example,  had  a  specific  gravity  of  1.030  before  fermenta- 
tion and  1.008  after,  then  the  quantity  of  sugar  contained  therein 
was  22  X  0.33  =  5.06^. 

In  performing  this  test  the  specific  gravity  must  be  taken  at  the 
same  temperature  before  and  after  the  fermentation.  The  urine 
must  be  faintly  acid,  and  when  necessary  it  should  be  acidified  with 
a  little  tartaric-acid  solution.  The  activity  of  the  yeast  must,  when 
necessary,  be  controlled  by  a  special  test.  Place  200  c.  c.  of  the 
Tirine  in  a  400-c.  c.  flask  and  add  a  piece  of  compressed  yeast  the 
size  of  a  pea,  and  subdivide  the  yeast  through  the  liquid  by  shak- 
ing, close  the  flask  with  a  stopper  provided  with  a  finely  drawn-out 
open  glass  tube,  and  allow  the  test  to  stand  at  the  temperature  of 
the  room,  or  still  better  at  +  20-25°  C.  After  24-48  hours  the 
fermentation  is  ordinarily  ended,  but  this  must  be  verified  by  the 
bismuth  test.  After  complete  fermentation  filter  through  a  dry 
filter,  bring  the  filtrate  to  the  proper  temperature,  and  determine 
the  specific  gravity. 

If  the  specific  gravity  be  determined  with  a  good  pyknometer 
supplied  with  a  thermometer  and  an  expansion-tube,  this  method, 
when  the  quantity  of  sugar  is  not  less  than  4-5  p.  m.,  gives,  accord- 
ing to  Worm  Muller,  very  exact  results,  but  this  has  been  disputed 
by  BuDDE.  For  the  physician  this  method  in  this  form  is  not 
serviceable.  Even  if  the  specific  gravity  is  determined  by  a  delicate 
urinometer  which  can  give  the  density  to  the  fourth  decimal,  we 
do  not  obtain  quite  exact  results  because  of  the  principal  errors 
of  the  method  (Budde)  ;  but  the  error  is  usually  smaller  than 
those  which  occur  in  titrations  made  by  unpractised  hands.  Among 
the  methods  proposed  and  closely  tested  for  the  quantitative  esti- 


THE   URINE.  419 

mation  of  sugar,  we  have  none  which  are  at  the  same  time  easily 
performed  and  which  give  positive  results  in  other  than  practised 
hands. 

When  the  quantity  of  sugar  is  less  than  5  p.  m.  these  methods 
cannot  be  used.  Such  a  small  amount  of  sugar  cannot,  as  above 
mentioned,  be  determined  by  titration  directly,  because  the  reduc- 
tion power  of  normal  urine  corresponds  to  4-5  p.  m.  In  such  cases, 
according  to  Worm  Muller,  first  determine  the  reduction  power  of 
the  urine  by  titration  with  Knapp's  solution,  then  ferment  the 
urine  with  the  addition  of  yeast,  and  titrate  again  with  Knapp's 
solution.  The  difference  found  between  the  two  titrations  calcu- 
lated as  sugar  gives  the  true  amount  of  sugar. 

Estimation  of  Sugar  by  Polarization.  In  this  method 
the  urine  must  be  clear,  not  too  deeply  colored,  and,  above  all,  must 
not  contain  any  other  optically-acting  substances  besides  glucose. 
By  using  a  delicate  instrument  and  witli  sufficient  practice  very 
exact  results  can  be  obtained  by  this  method  (K.  Morner,  H. 
Huppert).  For  the  physician,  Roberts'  fermentation  test,  which 
requires  no  expensive  apparatus  and  no  special  practice,  is  to  be  pre- 
ferred. Under  such  circumstances,  and  as  the  estimation  by  means 
of  polarization  can  be  performed  with  exactitude  only  by  specially- 
instructed  chemists,  it  is  hardly  necessary  to  give  this  method  in 
detail,  and  the  reader  is  referred  to  special  works  for  instructions  in 
the  use  of  the  apparatus. 

Levulose.  Lsevo-gyiate  urines  containing  sugar  have  been  observed  by 
Ventzke,  Zimmek  and  Czapek,  Seegen,  and  others.  The  nature  of  the  sub- 
stance causing  this  action  is  difficult  to  exactly  describe,  but  there  is  hardly  any 
doubt  that  the  urine,  at  least  in  certain  cases,  as  in  those  observed  by  Seegen, 
contains  levulose.  Leo  once  found  in  a  diabetic  urine  a  Isevo-gyrate,  reduci- 
ble, non-fermentable,  and  non-crystallizable  substance  which  was  considered 
by  him  as  a  peculiar  variety  of  sugar. 

The  presence  of  levulose  in  a  urine  containing  sugar  is  only  probable  when 
the  urine  is  lisevo-gyrate  or  optically  inactive,  or  when  it  shows  a  reduction 
power  not  corresponding  (less)  to  the  dextro-rotary  power,  or  when  it  contains 
no  other  Inevo-gyrate  substances  (/5-oxybutyric  acid,  coupled  glycuronic  acids, 
protein  bodies,  or  cystin). 

Milk-sugar.  The  appearance  of  milk-sugar  in  the  urine  of 
nursing  mothers  has  been  made  known  especially  by  the  investiga- 
tions of  De  Sijstety  and  F.  Hofmeister.  After  taking  large  quan- 
tities of  milk-sugar  some  lactose  was  found  in  the  urine  by  Worm 
MiJLLER,  and  De  Jong  found  also  glucose  under  the  same  circum- 
stances. 

The  positive  detection  of  milk-sugar  in  the  urine  is  difficult,  be- 
cause this  sugar  is,  like  glucose,  dextro-gyrate  and  also  gives  the 
usual  reduction  tests.     If  urine  contains  a  dextro-gyrate,  non-fer- 


420  PHYSIOLOGICAL   CHEMISTRY. 

mentable  sugar  which  reduces  bismuth  solutions,  then  it  is  very 
probable  that  it  contains  milk-sugar.  The  most  certain  means  for 
its  detection  is  to  isolate  the  sugar  from  the  urine.  This  may  be 
done  by  the  following  method,  suggested  by  F.  Hofmeistek. 

Precipitate  the  urine  with  sugar  of  lead,  filter,  wash  with  water,  unite  the 
fitrate  and  wash-water,  and  precipitate  with  ammonia.  The  liquid  filtered 
from  the  precipitate  is  again  precipitated  by  sugar  of  lead  and  ammonia,  until 
the  last  filtrate  is  optically  inactive.  The  several  precipitates  with  the  excep- 
tion of  the  first,  which  contains  no  sugar,  are  united  and  washed  with  water. 
The  washed  precipitate  is  decomposed  in  the  cold  with  sulphuretted  hydro- 
gen and  filtered.  The  excess  of  sulphuretted  hydrogen  is  driven  ofl:  by  a 
current  of  air  ;  the  acids  set  free  are  removed  by  shaking  with  silver  oxide. 
Now  filter,  remove  the  dissolved  silver  by  sulphuretted  hydrogen,  treat  with 
barium  carbonate  to  unite  with  any  free  acetic  acid  present,  and  concentrate. 
Before  the  evaporated  residue  is  syrupy  it  is  treated  with  90^  alcohol  until  a 
flocculent  precipitate  is  formed  which  settles  quickly.  The  filtrate  from  this 
when  placed  in  a  desiccator  deposits  crystals  of  milk-sugar,  which  are  purified 
by  recrystallization,  decolorizing  with  animal  charcoal  and  boiling  with  GO- 
TO^ alcohol. 

Ikosit  occurs  only  rarely,  and  only  in  small  quantities,  in  the 
urine  in  albuminuria  and  in  diabetes  mellitus.  After  excessive 
drinking  of  water  inosit  is  found  in  the  urine.  According  to 
Hoppe-Setlee,  traces  of  inosit  occur  in  all  normal  urines. 

In  detecting  inosit  the  albumin  is  first  removed  from  the  urine. 
Then  concentrate  the  urine  on  the  water-bath  to  \  and  precipitate 
with  sugar  of  lead.  The  filtrate  is  warmed  and  treated  with  lead 
acetate  as  long  as  a  precipitate  is  formed.  The  precipitate  formed 
after  24  hours  is  washed  with  water,  suspended  in  water,  and  de- 
composed with  sulphuretted  hydrogen.  A  little  uric  acid  may 
separate  from  the  filtrate  after  a  short  time.  The  liquid  is  filtered, 
concentrated  to  a  syrupy  consistency,  and  treated  while  boiling 
with  3-4  vols,  alcohol.  The  precipitate  is  quickly  separated.  After 
the  addition  of  ether  to  the  cooled  filtrate,  crystals  separate  after  a 
time,  and  these  are  purified  by  decolorization  and  recrystallization. 
with  these  crystals  perform  the  tests  mentioned  on  page  258. 

Aceton  and  Aceto-acetic  Acid.  These  bodies  were  first  observed 
in  urine  in  diabetes  mellitus  (Peters,  Kaulich,  v.  Jaksch,  Ger- 
hardt).  Both  of  these  bodies  occur  sometimes  simultaneously  in 
diabetic  urine,  sometimes  only  one  of  them.  Acetone  may  give 
the  diabetic  urine  as  well  as  the  expired  air  the  odor  of  apples  or 
fruit.  According  to  v.  Jaksch,  acetone  is  a  normal  urinary  con- 
stituent, though  it  may  only  occur  in  very  small  amounts  (0.1  grm. 


THE   URINE.  421 

in  the  24  hours).  Le  Nobel  claims  that  it  only  appears  in  healthy 
urine  after  taking  alcohol  or  after  food  rich  in  proteids.  Acetone 
as  well  as  aceto-acetic  acid  seems  to  be  a  decomposition  product  of 
the  albumins,  and  acetonuria  may  be  caused  by  food  very  rich  in 
proteids. 

In  regard  to  the  occurrence  of  these  bodies  under  diseased  con- 
ditions, a  great  many  observations  have  been  made,  especially  by 
V.  Jaksch,  Kaulich,  Cantani,  Deichmuller,  Frerichs,  Pen- 
ZOLDT,  Le  Nobel,  Seifert,  Gerhardt,  and  others.  Acetonuria 
occurs  in  certain  cases  of  diabetes,  and  especially  in  such  patho- 
logical processes  as  are  accompanied  by  an  increased  destruction  of 
the  tissues.  It  also  occurs  in  fevers,  in  cachectic  diseases,  some- 
times in  cancer  of  the  organs  of  digestion,  also  in  inanition  and  in 
psychosis.     Acetonuria  occurs  especially  often  in  children. 

Aceto-acetic  acid  never  occurs  in  the  urine  as  a  physiological 
constituent,  but  appears  under  the  same  circumstances  as  acetone. 
It  occurs  frequently  in  children,  in  high  fevers,  acute  exanthema, 
etc. 

Acetone,  dimethyl  ketone,  C'sHjO  or  CO,(CH3)2,  is  a  thin  water- 
clear  liquid  boiling  at  56.5°  C.  and  with  a  pleasant  odor  of  fruit. 
It  is  lighter  than  water,  with  which  it  mixes  in  all  proportions,  also 
with  alcohol  and  ether.  The  most  important  reactions  for  acetone 
are  the  following : 

LiEBEx's  Iodoform  Test.  When  a  watery  solution  of  acetone  is 
treated  with  alkali  and  then  with  some  iodine-potassium-iodide 
solution  and  gently  warmed  a  yellow  precipitate  of  iodoform  is 
formed,  which  is  known  by  its  odor  and  by  the  appearance  of  the 
crystals  (six-sided  plates  or  stars)  under  the  microscope.  This 
nation  is  very  delicate,  but  it  is  not  characteristic  of  acetone. 
Guxnixg's  modificafion  of  the  iodoform  test  consists  in  using  an 
alcoholic  solution  of  iodine  and  ammonia  instead  of  the  iodine  dis- 
solved in  potassium  iodide  and  alkali  hydrate.  In  this  case,  besides 
iodoform,  a  black  precipitate  of  iodide  of  nitrogen  is  formed,  but 
this  gradually  disappears  on  standing,  leaving  the  iodoform  visibla 
This  modification  has  the  advantage  that  it  does  not  give  any  iodo- 
form with  alcohol.  On  the  other  hand,  it  is  not  quite  so  delicate, 
but  still  it  detects  0.01  milligramme  acetone  in  1  cc. 

Reynold's  mercuric-oxide  test  is  based  on  the  power  of  acetone 


422  PHYSIOLOGICAL   CHEMI8TBT. 

to  dissolve  freshly-precipitated  HgO.  A  mercuric-cliloride  solution 
is  precipitated  by  alcoholic  caustic  potash.  To  this  add  the  liquid 
to  be  tested  for  acetone,  shake  well  and  filter.  In  the  presence  of 
acetone  the  filtrate  contains  mercury,  which  may  be  detected  by 
ammonium  sulphide.  This  test  has  about  the  same  delicacy  as 
Gunning's  test. 

Legal's  Sodium-nitroprusside  Test.  If  an  acetone  solution  is 
treated  with  a  few  drops  of  a  freshly-prepared  sodium-nitroprusside 
solution  and  then  with  caustic-potash  or  soda  solution,  the  liquid 
is  colored  ruby-red.  Creatinin  gives  the  same  color ;  but  if  we  sat- 
urate with  acetic  acid,  the  color  becomes  carmine  or  purplish  red  in 
the  presence  of  acetone,  but  yellow  and  then  gradually  green  and 
blue  in  the  presence  of  creatinin.  If  we  use  ammonia  instead  of 
the  caustic  alkali  (Le  Nobel),  the  reaction  takes  place  with  acetone 
but  not  with  creatinin.  Legal's  test  indicates  even  0.1  milligrm. 
acetone. 

Penzoldt's  indigo  test  depends  on  the  fact  that  orthonitroben- 
zaldehyde  in  alkaline  solution  with  acetone  yields  indigo.  A  warm 
saturated  and  then  cooled  solution  of  the  aldehyde  is  treated  with 
the  liquid  to  be  tested  for  acetone  and  then  with  caustic  soda. 
In  the  presence  of  acetone  the  liquid  first  becomes  yellow,  then 
green,  and  lastly  indigo  separates;  and  this  may  be  dissolved  with, 
a  blue  color  by  shaking  with  chloroform.  1.6  milligrms.  acetone 
can  be  detected  by  this  test. 

Aceto-acetic  Acid,  or  Diacetic  Acid,  O^HeOa  or  CgHsO.CHj. 
COOH.  This  acid  is  a  colorless,  strongly-acid  liquid  which  mixes 
with  water,  alcohol,  and  ether  in  all  proportions.  On  heating  to 
boiling  with  water,  and  especially  with  acids,  this  acid  decomposes 
into  carbon  dioxide  and  acetone,  and  therefore  gives  the  above- 
mentioned  reactions  for  acetone.  It  differs  from  acetone  in  that  it 
gives  a  violet-red  or  brownish-red  color  with  a  dilute  ferric-chloride 
solution.  This  color  decreases  even  at  the  ordinary  temperature 
within  24  hours,  and  more  quickly  on  boiling.  It  differs  in  this 
from  phenol,  salicylic  acid,  acetic  acid,  or  sulphocyanides. 

Detection  of  Acetone  and  Aceto-acetic  Acid  in  the  urine.  Before 
testing  for  aceto-acetic  acid  test  for  acetone,  and  as  this  acid  gradu- 
ally decomposes  on  allowing  the  urine  to  stand,  the  urine  must  be 
as  fresh  as  possible.     In  the  presence  of  aceto-acetic  acid  the  urine 


THE   URINE.  423 

gives  the  so-called  Gerhardt's  reaction,  showing  a  wine-red  color 
on  the  addition  of  a  dilute,  not  too  acid,  ferric-chloride  solution. 
Treat  10-5U  c.  c.  of  the  urine  with  ferric  chloride  as  long  as  it  gives 
a  precipitate,  filter  the  precipitate  of  ferric  phosphate,  and  add 
some  more  ferric  chloride  to  the  filtrate.  In  the  presence  of  the 
acid  a  claret-red  color  is  produced.  After  this  heat  a  second,  similar 
portion  of  the  urine  to  boiling  until  faint  acid  reaction,  and  repeat 
the  test  on  cooling,  which  should  7iow  give  negative  results.  A  third 
portion  of  urine  is  acidified  with  sulphuric  acid  and  shaken  with 
ether  (which  takes  up  the  acid).  Now  shake  the  removed  ether 
with  a  very  dilute  watery  solution  of  ferric  chloride,  and  the  watery 
layer  becomes  violet-red  or  claret-red.  The  color  disappears  on 
warming. 

In  the  absence  of  aceto-acetic  acid  the  acetone  may  be  tested  for, 
directly.  This  may  be  done  directly  on  the  urine  by  Legal's  and 
Penzoldt's  tests.  These  tests,  which  are  only  approximate  tests, 
are  only  of  value  when  the  urine  contains  a  considerable  amount  of 
acetone.  For  a  more  accurate  test  we  distil  at  least  250  c.  c.  of  the 
urine  faintly  acidified  with  sulphuric  acid,  care  being  taken  to  have 
a  good  condensation.  Most  of  the  acetone  is  contained  in  the  first 
10-20  c.  c.  of  the  distillate.  This  distillate  is  tested  for  acetone  by 
the  above  tests.  In  testing  for  acetone  in  the  simultaneous  pres- 
ence of  aceto-acetic  acid,  first  make  the  urine  faintly  alkaline,  and 
shake  it  carefully  with  ether  free  from  alcohol  and  acetone  in  a 
separatory  funnel.  The  removed  ether  is  then  shaken  with  water, 
which  takes  up  the  actone,  and  then  the  watery  liquid  is  tested. 

/S-Oxybutyric  Acid,  CHgOj  or  CH3.CH(0H).CH,.C00H.  The 
appearance  of  this  acid  in  the  urine  was  first  positively  shown  by 
MiNKOvrsKi,  KuLZ  and  Stadelmann.  It  occurs  especially  in  all 
difficult  cases  of  diabetes,  but  it  has  also  been  observed  in  scarlet 
fever  and  in  measles,  in  scurvy,  and  in  diseases  of  the  brain. 
/J-oxybutyric  acid  is  accompanied  by  aceto-acetic  acid  in  the 
urine. 

/?-oxybutyric  acid  forms  an  odorless  syrup  which  mixes  readily 
with  water,  alcohol,  and  ether.  This  acid  is  optically  active  and 
indeed  Isevo-gyrate,  and  it  therefore  interferes  with  the  estimation 
of  sugar  in  the  urine  by  means  of  polarization.  It  is  not  precip- 
itated either  by  lead  acetate  or  by  ammoniacal  basic  lead  acetate. 
On  boiling  with  water,  especially  in  the  presence  of  a  mineral 
acid,  this  acid  decomposes  into  a'-crotonic  acid,  which  melts  at 
71°-72°  C,  and  water:  CH3.Cn(0H).CHo.C00H  ^H^O  +  CH3.CH: 


424  PHYSIOLOGICAL   CHEMISTRY. 

CH.COOH.     It  yields  acetone  on  oxidation  with  a  chromate  mix- 
ture. 

Detection  of  ft-Oxyhutyric  Acid  in  the  urine.  If  a  urine  is  still 
lasvo-gyrate  after  fermentation  with  yeast,  the  presence  of  oxybu- 
tyric  acid  is  probable.  A  further  test  may  be  made,  according  to 
KULZ,  by  evaporating  the  fermented  urine  to  a  syrup,  and,  after  the 
addition  of  an  equal  volume  of  concentrated  sulphuric  acid,  distil- 
ling directly  without  cooling.  «-crotonic  acid  is  produced  which  is 
distilled,  and  after  strongly  cooling  the  distillate  is  collected  in  a 
glass;  crystals,  which  melt  at-)-  ''S"  C,  separate.  If  no  crystals 
are  obtained,  then  shake  the  distillate  with  ether,  and  test  the 
melting-point  with  the  residue,  which  has  been  washed  with  the 
water  obtained  after  evaporating  the  ether.  According  to  Min- 
kowski, the  acid  may  be  isolated  as  a  silver-salt  (see  Schmiede- 
berg's  Archiv,  18,  35,  or  Fresenius'  Zeitschrift,  34,  153). 

Ehrlich's  Urine  Test.  Mix  350  c.  c.  of  a  solution  which  contains  50  c.  c. 
HCl  and  1  grm.  sulphanilic  acid  in  one  litre  with  5  c.  c.  of  a  \%  solution  of 
sodium  nitrite  (which  produces  very  little  of  the  active  body,  sulphodiazoben- 
zol).  In  performiug  this  test  treat  the  urine  with  an  equal  volume  of  this 
mixture,  and  then  supersaturate  with  ammonia.  Normal  urine  will  become 
yellow  thereby,  or  orange  after  the  addition  of  ammonia  (aromatic  oxyacids 
may  sometimes  give  after  a  certain  time  red  azo  bodies  which  color  the  upper 
layer  of  phosphate  sediment).  In  pathological  urines  we  sometimes  have  (and 
this  is  the  characterislic  diazo  reaction)  a  primary  yellow  coloration,  with  a 
very  marked  secondary  red  coloration  on  the  addition  of  ammonia,  and  the 
froth  is  also  tinged  with  red.  The  upper  layer  of  the  sediment  becomes  green- 
ish. The  body  which  gives  this  reaction  is  unknown,  but  it  occurs  especially 
in  the  urine  of  typhus  patients  (Ehrlich).  Views  are  divided  in  regard  to 
the  significance  of  this  reaction  (Ehrlich,  Penzoldt,  Petri,  Escherik). 

Fat  in  the  urine.  The  elimination  of  a  urine  which  in  appearance  and 
richness  in  fat  resembles  chyle  is  called  cTiyluria.  It  contains  habitually  al- 
bumin, and  often  fibrin.  Chyluria  occurs  mostly  in  the  inhabitants  of  the 
trooics.  Lipuria,  or  the  elimination  of  fat  with  the  urine,  may  apj^ear  in  ap- 
parently healthy  persons,  sometimes  with  and  sometimes  without  albuminuria, 
in  pregnancy,  and  also  in  certain  diseases,  as  in  diabetes,  poisoning  with  phos- 
phorus, and  fatty  degeneration  of  the  kidneys. 

Fat  is  usually  detected  by  the  microscope.  It  may  also  be  dissolved  with 
ether,  and  it  may  always  be  detected  by  evaporating  the  urine  to  dryness  and 
extracting  the  residue  with  ether. 

Cholesterin  is  also  sometimes  found  in  the  urine  in  chyluria  and  in  a 
few  other  cases. 

Leucin  and  Tyrosin.     These  bodies  are  found  in  the  urine, 

especially  in  acute  yellow  atrophy  of  the  liver,  in  acute  phosphorus- 
poisoning,  and  in  difficult  cases  of  typhus  and  smallpox. 

Detection  of  leucin  and  tyrosin.  Tyrosin  occurring  as  sediment  may  be 
identified  by  means  of  the  microscope  ;  but  if  a  positive  proof  is  desired,  a 
recrystfillizalion  of  the  same  from  ammonia  or  ammoniacal  alcohol  is  necessary. 

To  detect  both  these  bodies  when  they  occur  in  solution  in  the  urine,  pro- 


TUE   URINE.  425 

ceed  in  the  following  manner  :  The  urine  free  from  albumin  is  precipitated 
by  basic  lead  acetate,  the  lead  removed  from  the  liltrate  by  HaS,  and  conceu- 
trated  as  much  as  possible.  The  residue  is  extracted  with  a  small  quantity  of 
absolute  alcohol  to  remove  the  urea.  The  re.sidue  is  then  boiled  with  faintly- 
ammoniacal  alcohol,  filtered,  the  filtrate  evaporated  to  a  small  volume  and 
allowed  to  crystallize.  If  no  tyrosin  crystals  are  obtained  then  dilute  with 
water,  precipitate  again  with  lead  acetate,  and  proceed  as  before.  If  tyrosin 
crystals  now  separate,  they  are  filtered  and  the  filtrate  still  further  concen- 
trated to  obtain  the  leucin  crystals. 

Cystin,  (C3H6NS02)2.     This  body  is,  according  to  Baumann,  to 

be  considered   as  disulphide^^^>C<g  ^^^^^>C<^^^^  of 

the  previously-mentioned  cystein,  C3H7NSO2  (page  393).  This  last 
substance,  containing  sulphur,  is  considered  by  Baumann  as  pyro- 
tartaric  acid,  whose  ketone-oxygen  atom  is  replaced  by  both  the 

monatomic  groups  NH^  and  SH  or  ^^-'^>S<^^^^. 

Baumann"  and  Goldmann  claim  that  a  substance  similar  to 
cystin  occurs  in  very  small  amounts  in  normal  urine.  Cystin  itself 
is  found  with  positiveness  only,  and  even  then  very  rarely,  in 
urinary  calculi  and  in  pathological  urines,  from  which  it  may 
separate  as  a  sediment.  Cystinuria  occurs  oftener  in  men  than  in 
women.  Cystin  seems  to  be  an  abnormal  splitting  product  of  the 
albumins.  Baumann  and  v.  Udeajstszky  found  in  urine  in 
cystinuria  the  two  diamins,  cadaverin  (pentamethylen-diamin) 
and  putrescin  (tetramethylen-diamin),  which  are  produced  in  the 
putrefaction  of  albumin  (Brieger).  These  two  diamins  were  also 
found  in  the  contents  of  the  intestine  in  cystinuria;  under  other 
conditions  they  are  not  usually  present.  The  author,  therefore, 
considers  that  some  connection  exists  between  the  formation  of 
diamins  in  the  intestine  by  the  peculiar  putrefaction  in  cystinuria, 
and  cystinuria  itself.  Diamins  have  also  been  found  in  the  con- 
tents of  the  intestines  in  cystinuria  by  Stadthagen  and  Briegefi. 

Cystin  crystallizes  in  thin,  colorless,  six-sided  plates.  It  is  not 
soluble  either  in  water,  alcohol,  ether,  or  acetic  acid,  but  dissolves 
in  mineral  acids  and  oxalic  acid.  It  also  dissolves  in  alkalies  and  in 
ammonia,  but  not  in  ammonium  carbonate.  Cystin  is  optically 
active  and  strongly  Isevo-rotary.  If  cystin  is  boiled  with  caustic 
alkali  it  decomposes,  yielding  among  other  products  alkali  sulphides, 
which  may  be  detected  by  lead  acetate  or  sodium  nitroprusside.    On 


426  PHYSIOLOGICAL  CHEMISTRT. 

treating  cystin  with  tin  and  hydrochloric  acid,  only  a  little  sulphu- 
retted hydrogen  is  evolved  and  cystein  is  produced.  On  shaking  a 
solution  of  cystin  in  an  excess  of  caustic  soda  with  benzoyl-chloride 
a  voluminous  precipitate  of  benzoyl-cystin  is  produced  (Baumann" 
and  GoLDMANN").  On  heating  on  a  platinum  foil,  cystin  does  not 
melt  but  ignites  and  burns  with  a  bluish-green  flame  accompanied 
by  a  peculiar  sharp  odor. 

Cystin  is  easily  prepared  from  cystin  calculi  by  dissolving  them 
in  alkali  carbonate,  precipitating  the  solution  with  acetic  acid,  and 
redissolving  the  precipitate  in  ammonia.  The  cystin  crystallizes  on 
the  spontaneous  evaporation  of  the  ammonia.  The  cystin  dissolved 
in  the  urine  is  detected,  in  the  absence  of  albumin  and  sulphu- 
retted hydrogen,  by  boiling  with  alkali  and  testing  with  lead  salt  or 
sodium  nitroprusside.  To  isolate  cystin  from  the  urine,  acidify  the 
urine  strongly  with  acetic  acid.  The  precipitate  containing  cystin 
is  collected  after  24  hours  and  digested  with  hydrochloric  acid, 
which  dissolves  the  cystin  and  calcium  oxalate,  leaving  the  uric 
acid  undissolved.  Filter,  supersaturate  the  filtrate  with  ammonium 
carbonate,  and  treat  the  precipitate  with  ammonia,  which  dissolves 
the  cystin  and  leaves  the  calcium  oxalate.  Filter  again  and  pre- 
cipitate with  acetic  acid.  The  precipitated  cystin  is  identified  by 
the  microscope  and  the  above-mentioned  reactions.  Cystin  as  a 
sediment  is  identified  by  the  microscope.  It  must  be  purified  by 
dissolving  in  ammonia  and  precipitating  with  acetic  acid  and  then 
tested.  Traces  of  dissolved  cystin  may  be  detected  by  the  produc- 
tion of  benzoyl-cystin,  according  to  Baumann  and  Goldmann. 


VII.    Urinary  Sediments  and  Calculi. 

Urinary  sediment  is  the  more  or  less  abundant  deposit  which  is 
found  in  the  urine  after  standing.  This  deposit  may  consist  partly 
of  organized  and  partly  of  non-organized  constituents.  The  first, 
consisting  of  cells  of  various  kiuds,  yeast-fungus,  bacteria,  sperma- 
tozoa, casts,  etc.,  must  be  investigated  by  means  of  the  microscope, 
and  the  following  only  applies  to  the  non-organized  deposits. 

As  above  mentioned  (page  331),  the  urine  of  healthy  individuals 
may  sometimes,  even  on  voiding,  be  cloudy  on  account  of  the  phos- 
phates present,  or  become  so  after  a  little  while  because  of  the  sepa- 
ration of  urates.  As  a  rule,  urine  just  voided  is  clear  and  after 
cooling  shows  only  a  faint   cloud  (nubecula),  which  consists  of 


THE  URINE.  427 

so-called  mucus,  a  few  epithelium-cells,  mucous  corpuscles,  and 
urate  particles.  If  au  acid  uriue  is  allowed  to  stand  it  will  gradu- 
ally change  ;  it  becomes  darker  and  deposits  a  sediment  consisting 
of  uric  acid  or  urates  and  sometimes  also  calcium-oxalate  crystals, 
in  which  yeast-fungus  and  bacteria  are  often  to  be  seen.  The 
cause  of  this  change,  which  the  earlier  investigators  called  "  acid 

FERMENTATION    OF    THE     URINE,"    is,    according    to    SCHERER,  the 

mucus,  which  acts  like  an  enzyme  or  ferment,  producing  an  acetic- 
acid  or  lactic-acid  fermentation,  precipitating  free  uric  acid  or  acid 
urates.  According  to  Neubauer,  an  actual  acid  fermentation  may 
occur  in  diabetic  urine,  but  this  change  in  the  urine  is  now 
generally  explained  in  other  ways.  According  to  VoiT  and  HoF- 
mann,  a  separation  of  free  uric  acid  and  acid  urates  may  be  pro- 
duced without  any  increase  in  the  acid  reaction,  by  an  exchange  of 
the  di-hydrogen  alkali  phosphates  with  the  alkali  urate  on  cooling 
and  on  standing.  Simple  acid  phosphate  and,  according  to  the 
conditions,  acid  urate  or  free  uric  acid  are  formed.  A  gradual  pre- 
cipitation of  uric  acid  may  occur  not  only  without  an  increase  in 
the  acid  reaction,  but,  because  of  the  alkaline  reaction  of  the 
di-alkali  phosphate,  it  may  occur  with  a  simultaneous  decrease  of 
the  same. 

Earlier  or  later,  sometimes  only  after  several  weeks,  the  reaction 
of  the  original  acid  urine  changes  and  becomes  neutral  or  alkaline. 
The  urine  has  now  passed  into  the  "alkaline  fermentation,^' 
which  consists  in  the  decomposition  of  the  urea  into  carbon  dioxide 
and  ammonia  by  means  of  lower  organisms,  micrococcus  nreae, 
bacteria  ure*,  and  other  bacteria.  Musculus  has  isolated  an 
enzyme  from  the  micrococcus  ure^  which  decomposes  urea  and  is 
soluble  in  water.  During  the  alkaline  fermentation  volatile  fatty 
acids,  especially  acetic  acid,  may  be  produced,  chiefly  by  the  fer- 
mentation of  the  carbohydrates  of  the  urine  (Salkowski). 

If  the  alkaline  fermentation  has  only  advanced  so  far  as  to 
render  the  reaction  neutral,  then  we  often  find  in  the  sediment 
fragments  of  uric-acid  crystals,  sometimes  covered  with  prismatic 
crystals  of  alkali  urate;  dark-colored  globules  of  ammonium  urate, 
often  crystals  of  calcium  oxalate,  and  sometimes  crystallized  cal- 
cium phosphate  are  also  found.  Crystals  of  ammonium-magnesium 
phosphate  (triple  phosphate)  and  globules  of  ammonium  urate  are 


428  PHYSIOLOGICAL  CHEMISTRY. 

specially  characteristic  of  the  alkaline  formentation.  The  urine  in 
alkaline  fermentation  becomes  paler  and  is  often  covered  with  a 
fine  membrane  which  contains  amorphous  calcium  phosphate  and 
glistening  crystals  of  triple  phosphate  and  numerous  micro-organ- 
isms. 

Non-organized  Sediments. 

Uric  Acid.  This  acid  occurs  in  acid  urines  as  colored  crystals 
which  are  identified  partly  by  their  form  and  partly  by  their  prop- 
erty of  giving  the  murexid  test.  On  warming  the  urine  they  are 
not  dissolved.  On  the  addition  of  caustic  alkali  to  the  sediment 
the  crystals  dissolve,  and  when  a  drop  of  this  solution  is  placed  on  a 
microscope-slide  and  treated  with  a  drop  of  hydrochloric  acid,  small 
crystals  of  uric  acid  are  obtained  which  are  easily  seen  under  the 
microscope. 

Acid  Urates.  These  only  occur  in  the  sediment  of  acid  or 
neutral  urines.  They  are  amorphous,  clay-yellow,  brick-red,  rose- 
colored,  or  brownish  red.  They  differ  from  other  sediments  in 
that  they  dissolve  on  warming  the  urine.  They  give  the  murexid 
test,  and  small  microscopic  crystals  of  uric  acid  separate  on  the 
addition  of  hydrochloric  acid.  Crystalline  alkali  urates  occur  very 
rarely  in  the  urine,  aivd  as  a  rule  only  in  such  as  have  become 
neutral  but  not  alkaline  by  the  alkaline  fermentation.  The  crys- 
tals are  somewhat  similar  to  those  of  neutral  calcium  phosphate, 
but  are  not  dissolved  by  acetic  acid  but  give  a  cloudiness  therewith 
due  to  small  crystals  of  uric  acid. 

Ammonium  urate  may  indeed  occur  as  a  sediment  in  a  neutral 
urine  which  at  first  was  strongly  acid  and  has  become  neutralized 
by  the  alkaline  fermentation,  but  it  is  only  characteristic  of  am- 
moniacal  urines.  This  sediment  consists  of  yellow  or  brownish, 
rounded  globules  which  are  often  covered  with  thorny-shaped 
prisms  and,  because  of  this,  are  rather  large  and  resemble  tlie  thorn- 
apple.  It  gives  the  murexid  test.  It  is  dissolved  by  alkalies  with 
the  development  of  ammonia,  and  crystals  of  uric  acid  separate  on 
the  addition  of  hydrochloric  acid  to  this  solution. 

Calcium  oxalate  occurs  in  the  sediment  generally  as  small, 
shining,  strongly-refractive-quadratic  octahedra,  which  on  micro- 
scopical examination  remind  one  of  a  letter-envelope.     The  crys- 


THE  URINE.  429 

tals  can  only  be  mistaken  for  small,  not  fully-developed  crystals  of 
ammonium-magnesium  phosphate.  They  differ  from  these  by 
their  insolubility  in  acetic  acid.  The  oxalate  may  also  occur  as 
flat,  oval,  or  nearly-circular  disks  with  central  cavities  which  from 
the  side  appear  like  an  hour-glass.  Calcium  oxalate  may  occur  as 
a  sediment  in  an  acid  as  well  as  in  a  neutral  or  alkaline  urine. 
The  quantity  of  calcium  oxalate  separated  from  the  urine  as 
sediment  depends  not  only  upon  the  amount  of  this  salt  present, 
but  also  upon  the  acidity  of  urine.  The  solvent  for  the  oxalate  in 
the  urine  seems  to  be  the  double-acid  alkali  phosphate,  and  the 
greater  the  quantity  of  this  suit  in  the  urine  the  greater  the 
quantity  of  oxalate  in  solution.  When,  as  above  mentioned  (page 
427),  the  simple-acid  phosphate  is  formed  from  the  double-acid 
phosphate,  on  allowing  the  urine  to  stand,  a  (Corresponding  part  of 
the  oxalate  may  be  separated  as  sediment. 

Calcium  carbonate  occurs  in  considerable  quantities  as  sediment 
in  the  urine  of  herbivora.  It  only  occurs  in  small  quantities  as  a 
sediment  in  human  urine,  and  indeed  only  in  alkaline  urines.  It 
has  either  almost  the  same  appearance  as  amorphous  calcium 
oxalate,  or  it  occurs  as  somewhat  larger  globules  with  concentric 
bands.  It  dissolves  in  acetic  acid  with  the  generation  of  gas,  which 
differentiates  it  from  calcium  oxalate.  It  is  not  yellow  or  brown 
like  ammonium  urate  and  does  not  give  the  niurexid  test. 

Calcium  sulphate  occurs  veiy  rarely  as  a  sediment  iu  strongly-acid  urines. 
It  appears  as  long,  thin,  colorless  needles,  or  generally  as  plates  grouped 
together. 

Calcium,  phosphate.  The  calcium  triphosphate,  Ca3(P04)2, 
which  only  occurs  in  alkaline  urines,  is  always  amorphous  and 
occurs  partly  as  a  colorless,  very  fine  powder  and  partly  as  a  mem- 
brane consisting  of  very  fine  granules.  It  differs  from  the  amor- 
phous urates  in  that  it  is  colorless,  dissolves  in  acetic  acid,  but 
remains  undissolved  on  warming  the  urine.  Calcium  diphos- 
phate, CaHPOi  -f  2II2O,  occurs  iu  neutral  or  only  in  very  faintly, 
acid  urine.  It  is  found  sometimes  as  a  thin  film  covering  the 
urine,  and  sometimes  as  a  sediment.  In  crystallizing  the  crystals 
may  be  single,  or  they  may  cross  one  another,  or  they  may  be  ar- 
ranged in  groups  of  colorless,  wedge-shaped  crystals  whose  wide  end 
is  sharply  defined.     These  crystals  differ  from  crystalline  alkaline 


430  PHTSIOLOOIGAL   CHEMISTRY. 

urates  in  that  they  dissolve  without  a  residue  in  dilute  acids  and 
do  not  give  the  murexid  test. 

Ammonium-jnagnesmm  pliospJiate,  triple  phosphate,  may 
separate  indeed  from  an  amphoteric  urine  in  the  presence  of  a  suf- 
ficient amount  of  ammonium  salts,  but  it  is  generally  characteristic 
of  an  ammoniacal  urine  from  alkaline  fermentation.  The  crystals 
are  so  large  that  they  may  he  seen  with  the  unaided  eye  as  colorless 
glistening  particles  in  the  sediment,  on  the  walls  of  the  vessel,  and 
in  the  film  on  the  surface  of  the  urine.  This  salt  forms  large 
prismatic  crystals  of  the  rhombical  system  which  are  easily  soluble 
in  acetic  acid.  Amorphous  magnesium  tripliosphate,  Mg3(P04)2, 
occurs  with  calcium  triphosphate  in  urines  rendered  alkaline  by 
a  fixed  alkali.  Crystalline  magnesium  phosphate,  Mg3(P04)2  + 
22H2O,  has  been  observed  in  a  few  cases  in  human  urine  (also  in 
horse^s  urine)  as  strongly-refractive,  long  rhombical  plates. 

Kyestem  is  the  film  which  appears  after  a  little  while  on  the  surface  of  the 
urine.  This  coating,  which  was  formerly  considered  as  characteristic  of  urine 
in  pregnancy,  contains  various  elements,  such  as  fungus,  vibriones,  epithelium- 
cells,  etc.     It  often  contains  earthy  phosphates  and  triple-phosphate  crystals. 

As  more  rare  sediments  we  find  cystin,  tyrosin,  hippuric  acid,  xanthin, 
hoBmatoidin.  In  alkaline  urines  blue  crystals  of  indigo  may  also  occur,  due  to 
a  decomposition  of  indoxyl-glycuronic  acid. 

Urinary  Calculi. 

Besides  certain  pathological  constituents  of  the  urine,  all  those 
urinary  constituents  which  occur  as  sediments  take  part  in  the  for- 
mation of  the  urinary  calculi.  Ebstein"  considers  the  essential 
difference  between  an  amorphous  or  crystalline  sediment  in  the 
urine  on  one  side  and  urinary  sand  or  large  calculi  on  the  other 
to  be  the  occurrence  of  an  organic  frame  in  the  last.  As  the  sedi- 
ments which  appear  in  normal  acid  urine,  and  in  an  alkaline  urine 
due  to  fermentation  are  different,  so  also  are  the  urinary  calculi 
which  appear  under  corresponding  conditions. 

If  the  formation  of  a  calculus  and  its  further  development  takes 
place  in  an  undecomposed  urine,  it  is  called  a  primary  formation. 
If,  on  the  contrary,  the  urine  has  undergone  alkaline  fermentation 
and  the  ammonia  formed  thereby  has  given  rise  to  a  calculous  for- 
mation by  precipitating  ammonium  urate,  triple  phosphate,  and 
earthy  phosphates,  then  it  is  called  a  secondary  formation.    Such 


THE   URINE.  431 

a  formation  takes  place,  for  instance,  when  a  foreign  body  in  the 
bladder  produces  catarrh  accompanied  by  alkaline  fermentation. 

We  discriminate  between  the  nucleus  or  nuclei — if  such  can  be 
seen — and  the  different  layers  of  the  calculus.  T^e  nucleus  may 
be  essentially  different  in  different  cases,  for  quite  frequently  it 
consists  of  a  foreign  body  introduced  into  the  bladder.  Tlie  calcu- 
lus may  have  more  than  one  nucleus.  In  a  tabulation  made  by 
Ultzmann  of  545  cases  of  urinary  calculi,  the  nucleus  consisted  in 
80.9^  of  the  cases,  of  uric  acid  (and  urates);  in  5.6^  of  calcium 
oxalate;  in  8. 6^  of  earthy  phosphates  ;  in  1.4^  of  cystin;  and  in 
3.3^  of  some  foreign  body. 

During  the  growth  of  a  calculus  it  often  happens  that,  for  some 
reason  or  other,  the  original  calculus-forming  substance  is  covered 
with  another  layer  of  a  different  substance.  A  new  layer  of  the 
original  substance  may  deposit  on  the  outside  of  this,  and  this  pro- 
cess may  be  repeated.  In  this  way  a  calculus  consisting  originally 
of  a  simple  stone  may  be  converted  into  a  so-called  compound  stone 
with  several  layers  of  different  substances.  Such  calculi  are  always 
formed  when  a  primary  formation  is  changed  into  a  secondary.  By 
the  continued  action  of  an  alkaline  urine  containing  pus,  the  prim- 
ary constituents  of  an  originally  primary  calculus  may  be  partly 
dissolved  and  be  replaced  by  phosphates.  Metamorphosed  urinary 
calculi  are  formed  in  this  way. 

Uric-acid  calculi  are  very  abundant.  They  are  variable  in  size 
and  form.  The  size  of  the  bladder-stone  varies  from  that  of  a  pea 
or  bean  to  that  of  a  goose-egg.  Uric-acid  stones  are  always  colored ; 
generally  they  are  grayish  yellow,  yellowish  brown,  or  pale  red- 
brown.  The  upper  surface  is  sometimes  entirely  even  or  smooth, 
sometimes  rough  or  uneven.  Next  to  the  oxalate  calculus,  the  uric- 
acid  calculus  is  the  hardest.  The  fractured  surface  shows  regular 
concentric,  unequally-colored  layers  which  may  often  be  removed 
as  shells.  These  calculi  are  formed  primarily.  Layers  of  uric-acid 
sometimes  alternate  with  other  layers  of  primary  formation,  most 
frequently  with  layers  of  calcium  oxalate.  The  simple  uric-acid 
calculus  leaves  very  little  residue  when  burnt  on  a  platinum  foil. 
It  gives  the  murexid  test,  but  there  is  no  mentionable  development 
of  ammonia  when  acted  on  by  caustic  soda. 

Am7notiium-urate  calculi  occur  as  primary  calculi  in  new-born 


432  PHYSIOLOGICAL   CHEMISTRY. 

or  nursing  infants,  rarely  in  grown  persons.  They  often  occur  as 
a  secondary  formation.  The  primary  stones  are  small,  with  a  pale- 
yellow  or  dark-yellowish  surface.  When  moist  they  are  almost  like 
dough  ;  in  the  dry  state  they  are  earthy,  easily  crumbling  into  a 
pale  powder.  They  give  the  murexid  test,  and  develop  much  am- 
monia with  caustic  soda. 

Calcium-oxalate  calculi  are,  next  to  uric-acid  calculi,  the  most 
abundant.  They  are  either  smooth  and  small  (hemp-seed  stone) 
or  larger,  of  the  size  of  a  hen's  egg,  with  rough,  uneven  surface,  or 
their  surface  is  covered  with  prongs  (mulberry  calculi).  These 
calculi  produce  bleeding  easily,  and  therefore  they  often  have  a 
dark-brown  surface  due  to  decomposed  blood-coloring  matters. 
Among  the  calculi  occurring  in  man  these  are  the  hardest.  They 
dissolve  in  hydrochloric  acid  without  developing  gas,  but  are  not 
soluble  in  acetic  acid.  After  gently  heating  the  powder  it  dissolves 
in  acetic  acid  with  frothing.  After  strongly  heating  the  powder  it 
is  alkaline,  due  to  the  production  of  quick-lime. 

Pliosfliate  Calculi.  These,  which  consist  mainly  of  a  mixture 
of  the  normal  phosphate  of  the  alkaline  earths  with  triple  phos- 
phate, may  be  very  large.  They  are  as  a  rule  of  secondary  forma- 
tion, and  contain  besides  these  phosphates  also  some  ammonium 
urate  and  calcium  oxalate.  These  calculi  ordinarily  consist  of  a 
mixture  of  these  three  constituents,  earthy  phosphate,  triple  phos- 
phate, and  ammonium  urate,  surrounding  a  foreign  body  as  a 
nucleus.  Their  color  is  variable — white,  dingy  white,  pale  yellow, 
sometimes  violet  or  lilac-colored  (from  indigo-red).  The  surface  is 
always  rough.  CaiCuli  consisting  of  triple  phosphate  alone  are  sel- 
dom found.  They  are  ordinarily  small,  with  granular  or  radiated 
crystalline  fracture.  Stones  of  simple-acid  calcium  phosphate  are 
also  seldom  obtained.  They  are  white  and  have  a  beautiful  crystal- 
line texture.  The  phosphatic  calculi  do  not  burn  up,  and  the  pow- 
der dissolves  in  acid  without  effervescence,  and  the  solution  gives 
the  reactions  for  phosphoric  acid  and  alkaline  earths.  The  triple- 
phosphate  calculi  generates  ammonia  on  the  addition  of  an  alkali. 

Calcium- carbonate  calculi  occur  chiefly  in  herbivora.  They  are  seldom 
found  in  man.  They  have  mostly  chalky  properties,  and  are  ordinarily  white. 
They  are  completely  or  in  great  part  dissolved  by  acids  vsdth  effervescence. 

Cystln  calculi  occur  but  seldom.  They  are  of  primary  formation,  of  vari- 
ous sizes,  sometimes  attaining  the  size  of  a  hen's  egg.    They  have  a  smooth  or 


THE  URINE.  433 

rough  surface,  are  white  or  pale  yellow,  and  have  a  crystalline  fracture.  They 
are  not  very  hard  ;  they  burn  up  almost  entirely  on  a  platinum' foil,  burning 
with  a  bluish  tiaine.     They  give  the  above-mentioned  reactions  for  cystin. 

Xanthin  calculi  are  ver}'  rarely  found.  They  are  also  of  primary  fonnation. 
They  vary  from  the  size  of  a  pea  to  that  of  a  hen's  egg.  They  are  whitish, 
yellowish  brown,  or  cinnamon-brown  in  color,  medium  hard,  with  amorphous 
fracture,  and  on  rubbing  appear  like  wax.  They  burn  up  completely  when 
heated  on  a  platinum  foil.  They  give  the  xanthin  reaction  with  nitric  acid 
and  alkali,  but  this  must  not  be  mistaken  for  the  murexid  test. 

Urosiealiih  calculi  have  only  been  observed  a  few  times.  In  the  moist  state 
the}"  are  soft  and  elastic  at  the  temperature  of  the  body,  but  in  the  dry  state 
they  are  brittle,  with  an  amorphous  fracture  and  waxy  appearance.  They 
burn  with  an  illuminating  tiame  when  heated  on  a  platinum  foil,  and  generate 
an  odor  similar  to  resin  or  shellac.  Such  a  calculus,  investigated  by  Kruken- 
BERG,  consisted  of  paraffiue  derived  from  a  parafhne  bougie  used  as  a  sound 
on  the  patient.  Perhaps  the  urostealith  calculi  observed  in  other  cases  had  a 
similar  origin,  although  the  substances  of  which  they  consisted  have  not  been 
closely  studied. 

Fib-rin  calculi  sometimes  occur.  They  consist  of  more  or  less  changed 
fibrin  coagulum.     On  ourniug  they  develop  an  odor  of  burnt  horn. 

The  chemical  investigation  of  urinary  calculi  is  of  great  practi- 
cal importance.  To  make  such  au  examination  actually  instructive 
it  is  necessary  to  investigate  separately  the  different  layers  which 
constitute  the  calculus.  For  this  purpose  saw  the  calcuhis,  which 
has  been  wrapped  in  paper,  with  a  fine  saw  so  that  the  nucleus  is 
sawed  through  and  accessible.  Then  peel  off  the  different  layers, 
or,  if  the  stone  is  to  be  kept,  scrape  off  enough  of  the  powder  from 
each  layer  for  examination.  Tins  powder  is  then  tested  by  heating 
on  a  platinum  foil.  It  must  not  be  forgotten  that  a  calculus  is 
never  entirely  burnt  up,  and  also  that  it  is  never  so  free  from 
organic  matter  that  on  heating  it  does  not  carbonize.  Do  not, 
therefore,  lay  too  great  stress  on  a  very  insignificant  unburut  residue 
or  on  a  very  small  amount  of  organic  matter,  but  consider  the  cal- 
culus in  the  former  case  as  completely  burnt  and  in  the  latter  as 
not  burnt. 

When  the  powder  is  in  great  part  burnt  up  but  a  significant 
quantity  of  unburnt  residue  remains,  then  the  powder  in  question 
contains  as  a  rule  urates  mixed  with  inorganic  bodies.  In  such 
cases  remove  the  urate  with  boiling  water,  and  then  test  the  filtrate 
for  uric  acid  and  the  expected  bases.  The  residue  is  then  tested 
according  to  the  following  schema  of  Helleb,  which  is  well  adapted 
to  the  investigation  of  urinary  calculi.  In  regard  to  more  detailed 
examination  the  reader  is  referred  to  special  works  on  the  subject. 


434 


PHYSIOLOGICAL   CHEMISTRY. 


On 

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CHAPTER    XV. 

THE  EXCHANGE  OF  MATERIAL  •  WITH   VARIOUS  FOODS  AND 
THE  DEMAND  FOR  FOOD  IN  MAN. 

The  conversion  of  chemical  tension  into  living  energy,  which 
characterizes  animal  life,  leads,  as  previously  stated  in  Chapter  I, 
to  the  formation  of  the  relatively  simple  compounds,  carbon 
dioxide,  urea,  etc.,  which  leave  the  organism  and  wliich  moreover, 
being  very  poor  in  chemical  tension,  are  for  tiiis  reason  of  no  or 
very  little  value  for  the  body.  It  is  therefore  absolutely  necessary 
for  the  continuance  of  life  and  the  normal  course  of  the  functions 
of  the  body,  that  the  organism  and  its  different  tissues  should  be 
supplied  with  new  material  to  replace  that  which  has  been  exhausted. 
This  is  accomplished  by  means  of  food.  Those  bodies  are  de- 
signated as  food  which  have  no  injurious  action  upon  the 
organism  and  which  replace  those  constituents  of  the  body  that  have 
been  consumed  in  the  exchange  of  material  or  that  can  prevent 
or  diminish  the  consumption  of  such  constituents. 

Among  the  numerous  dissimilar  substances  which  man  and 
animals  take  with  the  food  all  cannot  be  equally  necessary  or  have 
the  same  value.  Some  perhaps  are  unnecessary,  while  others  may 
be  indispensable.  We  have  learned  by  direct  observation  and  a 
wide  experience  that  besides  the  oxygen,  which  is  necessary  for 
oxidation,  the  essential  foods  for  animals  in  general,  and  for  man 
especially,  are  luateVy  mbieral  bodies^  proteid  bodies,  carbohydrateSy 
and  fats. 

It  is  also  apparent  that  the  various  groups  of  food-stuffs  neces- 

1  The  translator  will  use  in  the  following  pages  for  the  German  word 
"  Stoffwechsel"  Dr.  Burdou-Sanderson's  (Syllabus  of  Lectures,  1879)  transla- 
tion, exchange  of  material,  and  at  the  same  time  the  more  general  term 
"metabolism." 

435 


436  PHYSIOLOGICAL   CHEMI8TRT. 

sary  for  the  tissues  and  organs  must  be  of  different  importance; 
thus,  for  instance,  water  and  the  mineral  bodies  have  another  task 
tlian  the  organic  foods,  and  these  again  must  vary  in  importance 
among  themselves.  The  knowledge  of  the  action  of  various  nutri- 
tive bodies  on  the  exchange  of  material  from  a  qualitative  as  well 
as  a  quantitative  point  of  view  must  be  of  fundamental  importance 
in  determining  the  value  of  different  nutritive  substances  relative 
to  the  demands  of  the  body  for  food  under  various  conditions  and 
also  in  deciding  many  other  questions,  for  instance  the  proper 
nutrition  for  an  individual  in  health  and  in  disease. 

Such  knowledge  can  only  be  attained  by  a  series  of  systematic 
and  thorough  observations,  in  which  the  quantity  of  nutritive 
material,  relative  to  the  weight  of  the  body,  taken  and  absorbed  in 
a  given  time  is  compared  with  the  quantity  of  final  products  of  the 
exchange  of  material  which  leave  the  organism  at  the  same  time. 
Researches  of  this  kind  have  been  made  by  several  investigators,  but 
above  all  should  be  mentioned  those  made  by  Bischoff  and  Voit, 
by  Pettenkofer  and  Voit,  and  by  Voit  and  his  school. 

It  is  absolutely  necessary  in  researches  on  the  exchange  of 
material  to  be  able  to  collect,  analyze,  and  quantitatively  estimate 
the  excretions  of  the  organism  so  that  they  may  be  compared  with 
the  quantity  and  composition  of  the  nutritive  bodies  taken  up.  In 
the  first  place,  one  must  know  what  the  habitual  excretions  of  the- 
body  are  and  in  what  way  these  bodies  leave  the  organism.  One 
must  also  have  trustworthy  methods  for  the  quantitative  estimation 
of  the  same. 

The  organism  may,  under  physiological  conditions,  be  exposed 
to  accidental  or  periodic  losses  of  valuable  material — such  losses 
as  only  occur  in  certain  individuals,  or  in  the  same  individual  only 
at  a  certain  period;  for  instance,  the  secretion  of  milk,  the  produc- 
tion of  pus,  the  ejection  of  semen,  or  menstrul  blood.  It  is  therefore 
apparent  that  these  losses  can  only  be  the  subject  of  investigation 
and  estimation  in  special  cases. 

Tlie  regular  and  constant  excretions  of  the  organism  are  of  the 
very  greatest  importance  in  the  study  of  the  exchange  of  material. 
To  these  belong,  in  the  first  place,  the  true  final  products  of  the 
exchange — carbon"  dioxide,  urea  (uric  acid,  hippuric  acid, 
creatinin,  and  other  urinary  constituents),  and  a  part  of  the  water. 


EXCHANGE  OF  MATERIAL.  437 

The  remainder  of  tlie  water,  the  mineral  bodies,  and  those  secretions 
or  tissue-constituents — mucus,  digestive  fluids,  sebum,  sweat, 
and  EPIDERMIS  FORMATIONS — which  are  either  poured  into  the 
intestinal  tract,  or  secreted  from  the  surface  of  the  body,  or  broken 
off  and  thereby  lost  for  the  body,  also  belong  to  the  constant  excreta. 
The  remains  of  food,  sometimes  indigestible,  sometimes  digest- 
ible but  not  acted  upon,  contained  in  the  faeces,  which  vary  in 
quantity  and  composition  with  the  nature  of  tlie  food,  also  belong 
to  the  excreta  of  the  organism.  Even  though  these  remains,  which 
are  never  absorbed  and  therefore  are  never  constituents  of  the 
animal  fluids  or  tissues,  cannot  be  considered  as  excreta  of  the  body 
in  a  strict  sense ;  still  their  quantitative  estimation  is  absolutely 
necessary  in  experiments  on  the  exchange  of  material. 

The  determination  of  the  constant  loss  is  in  some  cases  accom- 
panied with  the  greatest  difficulties.  The  loss  from  the  detached 
epidermis,  from  the  secretion  of  the  sebaceous  glands,  etc.,  cannot 
be  determined  with  exactness  without  difficulty,  and  therefore — as 
they  do  not  occasion  any  mentionable  loss  because  of  their  small 
quantity — they  need  not  be  considered  in  quantitative  experiments 
on  the  exchange  of  material.  This  also  applies  to  the  constituents 
of  the  mucus,  bile,  pancreatic  and  intestinal  juices,  etc.,  occurring 
in  the  contents  of  the  intestines  and  which,  leaving  the  body  with 
the  faeces,  cannot  be  separated  from  the  other  contents  of  the 
intestines  and  therefore  cannot  be  quantitatively  determined  sepa- 
rately. The  uncertainty  which,  because  of  the  intimated  difficulties, 
attaches  itself  to  the  results  of  the  experiments  is  very  small  as 
compared  to  the  variation  which  is  caused  by  different  individuali- 
ties, different  modes  of  living,  different  foods,  etc.  No  general  but 
only  approximate  value  can  therefore  be  given  for  the  constant 
excretions  of  the  human  body. 

The  following  figures  represent  the  quantity  of  excreta  for 
24  hours,  with  a  mixed  diet,  of  a  grown  man  weighing  60-70  kilos. 
The  numbers  are  compiled  from  the  results  of  different  investi- 
gators. Grammes. 

Water 2500-3500 

Salts  (with  the  urine) 20-30 

Carbon  dioxide 750-900 

Urea 20-40 

Other  nitrogenized  urinary  constituents 2-5 

Solids  in  the  excrements  30-50 


438  PHYSIOLOGICAL   CHEMI8TBT. 

These  total  excreta  are  approximately  divided  among  the  various 
excretions  in  the  following  way — but  still  it  must  not  be  forgotten 
that  this  division  may  vary  to  a  great  extent  under  various  external 
circumstances:  by  eespiratio^st  about  32^  by  the  evaporation" 
FROM  THE  SKIN  11  fo,  with  the  URINE  46-47^  and  with  the  excre- 
ments 5-9^.  The  elimination  by  the  skin  and  lungs,  which  is 
sometimes  differentiated  by  the  name  "  perspiratio  insensibilis" 
from  the  visible  elimination  by  the  kidneys  and  intestine,  is  on  an 
average  about  50^  of  the  total  elimination.  This  proportion,  only 
quoted  relatively,  is  subject  to  considerable  variation,  because  of  the 
great  difference  in  the  loss  of  water  through  the  skin  and  kidneys 
under  different  circumstances. 

About  90^  of  the  water  in  carnivora  is  excreted  through  the 
kidneys.  In  herbivora  the  excrements,  which  are  30-50^  of  the 
total  excreta,  may  indeed  eliminate  60^  of  the  water.  In  man  only 
a  smaller  fraction  of  the  water  (about  b%)  is  eliminated  with  the 
fasces,  and  the  great  mass  of  the  water  is  divided  between  the  kid- 
neys, lungs,  and  skin. 

The  nitrogenized  constituents  of  the  excretions  consist  chiefly 
of  urea,  or  uric  acid  in  certain  animals,  and  the  other  nitrogenized 
urinary  constituents.  A  disproportionally  large  part  of  the  nitrogen 
leaves  the  body  with  the  urine;  and  as  the  nitrogenized  constitu- 
ents of  this  excretion  are  final  products  of  the  transformation  or 
metabolism  of  proteids  in  the  organism,  the  quantity  of  proteids 
transformed  in  the  body  may  be  easily  calculated  by  multiply- 
ing the  quantity  of  nitrogen  in  the  urine  by  the  coefficient 
6.25  (ijpg"  =  6.25),  if  we  admit  that  the  proteids  contain  in  round 
numbers  16^  nitrogen. 

Still  another  question  is  whether  the  nitrogen  leaves  the  body 
only  with  the  urine  or  by  other  channels.  This  last  is  habitually 
the  case.  The  discharges  from  the  intestine  always  contain  some 
nitrogen  which  has  a  twofold  origin.  A  part  of  this  nitrogen  de- 
pends upon  undigested  or  non-absorbed  remnants  of  food,  and  an- 
other part  on  the  non-absorbed  remains  of  digestive  secretions — 
bile,  pancreatic  Juice,  intestinal  mucus — and  of  epithelium-cells  of 
the  mucous  membrane.  It  follows  that  a  part  of  the  nitrogen  of 
faeces  has  this  last-mentioned  origin  from  the  fact  that  discharges 
from  the  intestine  occurs  also  in  complete  inanition. 


EXCHANGE  OF  MATERIAL.  439 

If  the  question  to  be  decided  is,  how  much  of  the  nitrogenized 
bodies  is  absorbed  in  certain  modes  of  nutrition  or  after  taking  a 
certain  quantity  of  food,  then  naturally  the  quantity  of  nitrogen 
originating  from  the  food  and  leaving  the  body  with  the  excre- 
ments must  be  subtracted  from  the  total  quantity  of  nitrogen  taken 
up  with  the  food.  To  obtain  the  quantity  of  nitrogen  leaving  the 
body  with  the  excrements  it  is  necessary  to  subtract  from  the  total 
quantity  of  nitrogen  of  the  excrements  the  quantity  of  nitrogen 
coming  from  the  digestive  tract  itself  and  its  secretions,  and  the 
amount  of  this  last  must  be  known. 

It  is  obvious  that  exact  results  which  answer  for  all  times  can- 
not be  given  for  that  part  of  the  nitrogen  which  has  its  origin  in 
the  digestive  canal  and  fluids.  It  may  not  only  vary  in  different 
individuals,  but  also  in  the  same  individual  after  more  or  less  active 
secretion  and  absorption.  In  the  attempts  made  to  determine  this 
part  of  the  nitrogen  of  the  excrements  it  has  been  found  that  in 
man,  on  non-nitrogenized  or  nearly  nitrogen-free  food,  it  amounts 
in  round  numbers  to  about  1  grm.  per  24  hours  (Eieder;  Rubner). 
During  starvation,  in  which  a  smaller  quantity  of  digestive  secre- 
tions is  eliminated,  it  is  less.  MIjller  found  in  his  observations 
on  the  faster  Cetti  that  only  0.2  grm.  nitrogen  was  derived  from 
the  intestinal  canal. 

Xitrogen  also  leaves  the  body  through  the  horn  formation.  The 
quantity  which  is  lost  in  this  manner  is,  though  it  cannot  be  ex- 
actly determined,  insignificant.  Man  loses  only  about  0.3  grm. 
nitrogen  daily  by  means  of  the  hair  and  nails  (Moleschott)  and 
about  0.3-0.5  grm.  by  the  scaling-off  of  the  skin.  The  quantity  of 
nitrogen  which  leaves  the  body  under  ordinary  circumstances  by 
the  perspiration  must  be  so  small  that,  like  the  loss  by  the  horny 
structure,  it  need  not  be  considered  in  experiments  on  the  exchange 
of  material.  The  elimination  of  nitrogen  by  the  perspiration  need 
only  be  considered  in  cases  of  profuse  sweating. 

The  view  was  formerly  held  that  in  man  and  carnivora  an  elim- 
ination of  gaseous  nitrogen  took  place  through  the  skin  and  lungs, 
and  because  of  this,  on  comparing  the  nitrogen  of  the  food  with 
that  of  the  urine  and  fasces,  a  nitrogen  deficit  occurred  in  the  vis- 
ible elimination. 

This  question  has  been  the  subject  of  much  discussion  and  of 


440  PHYSIOLOGICAL   CHEMISTRY. 

numerous  investigations.  The  conclusion  has  been  drawn  from 
the  researches  of  Regnault  and  Reiset  on  respiration  that  also 
an  exhalation  of  nitrogen  takes  place.  Seegen  and  Nowak  espe- 
cially have  recently  endeavored  to  prove  the  correctness  of  this  con- 
clusion. Such  an  experiment  is,  however,  accompanied  with  so 
many  diflBculties,  and  there  are  so  many  sources  of  error,  that  it  can 
scarcely  be  considered  as  conclusive.  In  fact,  Pettenkofee  and 
VoiT  have  demonstrated  the  existence  of  errors  in  the  experiments 
of  Seegen  and  Now^ak.  On  the  other  hand,  PFLiJGER  and  Leo 
have  found  no  appreciable  exhalation  of  nitrogen' in  rabbits.  Also 
many  investigators,  especially  VoiT,  Pettenkoper  and  Voit  and 
Eanke,  have  shown  by  experiments  on  man  that  with  the  proper 
amount  and  quality  of  food  we  can  bring  the  body  into  liiriTROGE- 
ifous  EQUILIBRIUM,  in  which  the  quantity  of  nitrogen  voided  with 
the  urine  and  fseces  is  equal  to  the  quantity  contained  in  the  food. 

The  experiments  made  by  Gruber  in  Voit's  institute  seem  to 
be  especially  conclusive  on  this  point.  Grubbr  fed  a  dog  seventeen 
days  on  meat  which  in  all  contained  368.53  grms.  nitrogen,  and  he 
found  in  the  same  time  368.28  grms.  nitrogen  in  the  urine  and 
fseces.  From  this  and  other  experiments  we  may  conclude  with 
Voit  that  a  deficit  of  nitrogen  does  not  exist;  or  if  we  consider  the 
above-mentioned  very  small  loss  of  nitrogen  through  the  horny 
structure,  etc.,  it  is  so  insignificant  that  in  experiments  upon  the 
exchange  of  material  it  need  not  be  considered.  In  investigations 
on  the  metabolism  of  proteids  in  the  body,  ordinarily,  it  is  only 
necessary  to  consider  the  nitrogen  of  the  urine  and  fseces,  but  it 
must  be  remarked  that  the  nitrogen  of  the  urine  is  a  measure  of  the 
«extent  of  the  metabolism  of  the  proteids  in  the  body,  while  the 
nitrogen  of  the  fseces  (after  deducting  somewhat  less  than  1  grm. 
on  mixed  diet)  is  a  measure  of  the  non-absorbed  part  of  the  nitrogen 
of  the  food. 

In  the  oxidation  of  the  proteids  in  the  organism  their  sulphur 
is  oxidized  into  sulphuric  acid,  and  on  this  depends  the  fact  that 
the  elimination  of  sulphuric  acid  by  the  urine,  which  in  man  is 
only  to  a  small  extent  derived  from  the  sulphates  of  the  food,  makes 
nearly  equal  variations  as  the  elimination  of  nitrogen  by  the  urine. 
If  we  consider  the  amount  of  nitrogen  and  sulphur  in  the  proteids 
as  16^  and  1^  respectively,  then  the  proportion  between  the  nitrogen 


EXCHANGE  OF  MATERIAL.  441 

of  the  proteids  and  the  sulphuric  acid,  HgSO^,  produced  by  their 
burning,  is  in  the  ratio  5.2:1,  or  about  the  same  as  in  the  urine 
(see  page  382).  The  determination  of  the  quantity  of  sulphuric 
acid  eliminated  with  the  urine  gives  us  an  important  means  of  con- 
trolling the  extent  of  the  transformation  of  proteids,  and  such  a 
control  is  especially  important  in  cases  in  which  we  wish  to  study 
the  action  of  certain  nitrogenized  non-albuminous  bodies  on  the 
metabolism  of  proteids.  A  determination  of  the  nitrogen  alone  is 
not  in  such  cases  sufficient. 

If  it  is  found,  on  comparing  the  nitrogen  of  the  food  with  that  of 
the  urine  and  faeces,  that  there  is  an  excess  of  the  first,  this  means 
that  the  body  has  increased  its  stock  of  nitrogenized  substances — 
proteids.  If,  on  the  contrary,  the  urine  and  faeces  contain  more 
nitrogen  than  the  food  taken  at  the  same  time,  this  denotes  that 
the  body  is  giving  up  part  of  its  nitrogen — that  is,  a  part  of  its  own 
proteids.  We  can  from  the  quantity  of  nitrogen,  as  above  stated, 
calculate  the  corresponding  quantity  of  proteids  by  multiplying  by 
6.25.  Usually,  according  to  Voit's  proposition,  the  nitrogen  of 
the  urine  is  not  calculated  as  decomposed  proteids,  but  as  decom- 
posed muscle-substance.  Flesh  contains  on  an  average  about  3.4^ 
nitrogen,  and  each  gramme  of  nitrogen  of  the  urine  corresponds  in 
round  numbers  to  about  30  grms,  flesh. 

A  disproportionally  large  part  of  the  carbon  leaves  the  body  as 
carbon  dioxide,  which  escapes  chiefly  through  the  lungs  and  skin. 
The  remainder  of  the  carbon  is  eliminated  under  the  form  of 
organic  combinations  by  the  urine  and  fseces,  in  which  the  quantity 
of  carbon  can  be  determined  by  elementary  analysis.  The  amount 
of  gaseous  carbon  dioxide  eliminated  is  determined  by  means  of 
Pettenkofer's  respiration  apparatus,  which  is  described  in  special 
works.  By  multiplying  the  quantity  of  carbon  dioxide  found  by 
0.273  we  obtain  the  quantity  of  carbon  eliminated  as  CO2.  If  we 
compare  the  total  quantity  of  carbon  eliminated  in  various  ways 
with  the  carbon  contained  in  the  food,  we  obtain  some  idea  as  to 
the  transformation  of  the  carbon  compounds.  If  the  quantity  of 
carbon  in  the  food  is  greater  than  in  the  excretion,  then  the  excess 
is  deposited;  while  if  the  reverse  be  the  case,  it  shows  a  correspond- 
ing loss  of  bodily  substance. 

The  nature  of  the  substances  here  deposited  or  lost,  whether 


442  PHYSIOLOGICAL   CHEMISTRY. 

they  consist  of  proteids,  fats,  or  carbohydrates,  is  learned  from  the 
total  quantity  of  nitrogen  of  the  excretions.  The  corresponding 
quantity  of  proteids  may  be  calculated  from  the  quantity  of  nitro- 
gen, and  as  the  average  quantity  of  carbon  in  the  proteids  is  known, 
the  quantity  of  carbon  which  corresponds  to  the  decomposed  pro- 
teid  may  be  easily  ascertained.  If  the  quantity  of  carbon  found  is 
smaller  than  the  quantity  of  the  total  carbon  in  the  excretions,  it  is 
then  obvious  that  some  other  nitrogen-free  substance  has  been  con- 
sumed besides  the  proteids.  If  the  amount  of  carbon  in  the  pro- 
teids is  considered  in  round  numbers  as  54^,  then  the  relation 
between  carbon  (54)  and  nitrogen  (16)  is  as  3.4:1.  Multiply  the 
total  quantity  of  nitrogen  eliminated  by  3.4,  and  the  excess  of 
carbon  in  the  eliminations  over  the  product  found  represents  the 
carbon  of  the  transformed  non-nitrogeuized  compounds.  For 
instance,  in  the  case  of  a  person  experimented  upon,  10  grms.  nitro- 
gen and  200  grms.  carbon  were  eliminated  in  the  course  of  24  hours; 
then  these  62.5  grms.  proteid  correspond  to  34  grms.  carbon,  and 
the  difference  200  —  (3.4x10)  =  166,  which  represents  the  quantity 
of  carbon  in  the  decomposed  non-nitrogenized  compounds.  If  we 
start  from  the  simplest  case,  starvation,  where  the  body  lives  at  the 
expense  of  its  own  substance,  then,  since  the  quantity  of  carbohy- 
drates as  compared  to  the  fats  of  the  body  is  extremely  small,  in 
such  cases  in  order  to  avoid  mistakes  the  assumption  must  be  made 
that  the  person  experimented  upon  has  only  taken  fat  and  proteids. 
As  animal  fat  contains  on  an  average  76.5^  carbon,  the  quantity  of 
transformed  fat  may  be  calculated  by  multiplying  the  carbon  by 

— —  =  1.3.      In    the    case    of    the    above    example    the    person 

experimented  upon  would  have  used  62.5  grms.  proteids '  and 
166  X  1.3  =  216  grms.  fat  of  his  own  bodily  weight  in  the  course 
of  the  24  hours. 

Starting  from  the  balance  of  the  nitrogen,  we  can  calculate  in 
the  same  way  whether  an  excess  of  carbon  in  the  food  as  compared 
with  the  quantity  of  carbon  in  the  excretions  is  retained  by  the 
body  as  proteids  or  fat  or  as  both.  On  the  other  hand,  with  an 
excess  of  carbon  in  the  excretions  we  can  calculate  how  much  of  the 
loss  of  the  substance  of  the  body  is  due  to  a  consumption  of  the 
proteid  or  of  fat  or  of  both. 


EXCHANGE  OF  MATERIAL.  443 

The  quantity  of  water  and  mineral  bodies  voided  with  the  urine 
and  faBces  can  easily  be  determined.  The  quantity  of  water  elimi- 
nated by  the  skin  and  lungs  may  be  directly  determined  by  means 
of  PettenKofer's  apparatus.  The  quantity  of  oxygen  taken  up  is 
calculated  as  the  difference  between  the  weight  of  the  individual 
before  the  experiment  plus  all  the  directly-determined  substances 
taken  in,  and  the  final  weight  of  the  individual  plus  all  his  excreta, 

I.   Exchange  of  Material  in  Starvation, 

In  starvation  the  decomposition  in  the  body  continues  uninter- 
ruptedly, though  with  decreased  intensity;  but  as  it  takes  place  at 
the  expense  of  the  substance  of  the  body,  it  can  only  continue  for  a 
limited  time.  When  an  animal  has  lost  a  certain  fraction  of  the  mass 
of  tlie  body  death  is  the  result.  This  fraction  varies  with  the  condi- 
tion of  the  body  at  the  beginning  of  the  starvation  period.  Fat  ani- 
mals succumb  when  the  weight  of  the  body  has  sunk  to  I-  of  the  orig- 
inal weight.  Otherwise,  according  to  Chossat,  animals  die  as  a  rule 
when  the  weight  of  the  body  has  sunk  to  -|  of  the  original  weight. 
The  period  when  death  occurs  from  starvation  not  only  varies  with 
the  different  nutritive  condition  at  the  beginning  of  starvation,  but 
also  with  the  more  or  less  active  exchange  of  material.  This  is  more 
active  in  small  and  young  animals  than  in  large  and  older  ones,  but 
different  classes  of  animals  show  an  unequal  activity.  Children 
succumb  in  starvation  in  three  to  five  days  after  having  lost  I  of 
their  bodily  mass.  Grown  persons,  according  to  ordinary  state- 
ments, can  live  for  three  weeks  if  they  have  water  ;  we  also  have 
statements  of  much  longer  periods  of  starvation.  For  instance,  a 
person  suffering  from  melancholia,  who  drank  water  but  took  no 
food,  died  after  41  days,  and  the  Italian  Meelatti  withstood  a 
starvation  period  of  50  days,  during  which  it  is  stated  he  only  took 
water.  Dogs  can  live  without  food  from  four  to  eight  weeks,  birds 
five  to  twenty  days,  snakes  more  than  half  a  year,  and  frogs  more 
than  a  year. 

In  stiirvation  the  weight  of  the  body  decreases.  The  loss  of 
weight  is  greatest  in  the  first  few  days,  and  then  decreases  rather 
uniformly.  In  small  animals  the  absolute  loss  of  weight  per  day  is 
naturally  smaller  than  in  larger  animals.   The  relative  loss  of  weight, 


444  PHYBIOLOQICAL   CHEMISTS  Y. 

that  is,  the  loss  of  weight  of  the  unit  of  the  weight  of  the  body, 
namely  1  kilo,  is,  on  the  contrary,  greater  in  small  animals  than  in 
larger  ones.  The  reason  for  this  is  that  the  smaller  animals  have  a 
greater  surface  of  body  in  proportion  to  their  mass  than  larger 
animals,  and  the  greater  loss  of  heat  caused  hereby  must  be  replaced 
by  a  more  active  consumption  of  material  (Eubnee). 

Exact  observations  for  a  long  time  are  necessary  for  a  thorough 
study  of  the  exchange  of  material  in  starvation.  As  these  have 
seldom  been  made  on  man  our  knowledge  of  the  exchange  of 
material  in  starvation  has  been  gained  by  observations  on  animals, 
especially  on  carnivora. 

As  the  exchange  of  material  in  starvation  takes  place  at  the 
expense  of  the  constituents  of  the  body,  it  must  take  place  in 
essentially  the  same  way  in  both  carnivora  and  herbivora.  As  the 
food  of  the  herbivora  is  ordinarily  richer  in  carbohydrates  and  non- 
nitrogenized  nutritive  bodies  than  that  of  the  carnivora,  so  in  star- 
vation the  body  of  the  herbivora  becomes  relatively  richer  in 
proteids.  On  this  account  the  elimination  of  urea  is  increased  in 
herbivora  in  the  first  part  of  the  period  of  starvation.  In  carniv- 
ora the  elimination  of  urea  decreases,  as  a  rule,  immediately  at  the 
beginning  of  the  starvation,  and  in  the  later  periods  only  small 
amounts  of  urea  are  voided  by  herbivora  as  well  as  by  carnivora. 

The  extent  of  the  metabolism  of  proteids  and  the  elimination  of 
urea,  which  is  a  measure  for  the  same,  does  not  show  in  carnivora 
any  uniform  decrease  during  the  entire  period  of  starvation. 
During  the  first  few  days  the  elimination  of  nitrogen  is  greatest 
and  the  quantity  of  the  same  depends  essentially  upon  the  amount 
of  proteids  in  the  organism  and  the  nature  of  the  food  previously 
taken.  The  richer  the  body  is  in  proteids  from  the  food  previously 
taken  the  greater  is  the  metabolism  of  proteids,  or,  in  other  words, 
the  elimination  of  nitrogen  during  the  first  days  of  starvation  is 
greater.  The  rapidity  with  which  the  elimination  of  nitrogen 
decreases  in  the  first  days  depends  also,  according  to  Voit,  upon 
the  proteid  condition  of  the  body.  It  decreases  more  quickly, 
that  is,  the  curve  of  the  decrease  is  more  sudden,  the  first  days  of 
starvation,  as  a  rule,  the  richer  the  food  was  in  proteids  which  was 
taken  before  starvation.  This  condition  is  apparent  from  the  fol- 
lowing table.     This  table  contains  three  different  starvation  experi- 


EXCHANGE  OF  MATERIAL.  445 

ments  made  by  Voit  on  the  same  dog.  This  dog  received  2500 
grms.  flesh  daily  before  the  first  series  of  experiments,  1500  grms. 
flesh  daily  before  the  second  series,  and  a  mixed  food  relatively 
poor  in  nitrogen  before  the  tliird  series. 

TABLE   I. 

Flaw  r,t  fitar-vaiinn  Gramiues  of  Urea  eliminated  in  the  Twenty-four  Hours. 

Day  or  htarvation.  g^^  j  g^^.  jj  ^^^  ^^ 

1 60.1  36  5  13.8 

2 24.9  18.6  11.5 

3 19.1  15.7  10.2 

4 17.3  14  9  12.2 

5 12.3  14.8  12.1 

6 13.3  12.8  12.6 

7 12.5  12.9  11.3 

8 10.1  12.1  10.7 

Other  conditions,  such  as  varying  amounts  of  fat  in  the  body, 
have  an  influence  on  the  rapidity  with  which  the  nitrogen  is 
eliminated  during  the  first  days  of  starvation.  After  the  first  few 
days  the  elimination  of  nitrogen,  as  is  seen  in  the  above  table,  is 
more  uniform,  and  as  the  starvation  proceeds  it  decreases  as  a  rule 
very  slowly  and  uniformly.  Cases  also  occur  in  which  the  elimina- 
tion of  nitrogen  becomes  constant  in  these  stages,  and  in  which 
indeed  the  elimination  of  nitrogen  increases  towards  the  end. 
This  so-called  premortal  increase  always  occurs  as  soon  as  the 
adipose  tissue  in  the  body  has  sunk  to  a  certain  point,  and  it  also 
depends  on  the  fact  that  as  soon  as  the  fat  is  consumed  a  corre- 
sponding increase  in  the  decomposition  of  proteids  is  necessary  for 
the  generation  of  heat  as  well  as  of  other  forces. 

If  fat  occurs  in  the  body  besides  proteids,  it  is  also  decomposed 
in  starvation.  Since  fat  has  a  diminishing  influence  on  the  de- 
struction of  proteids  (see  further  on),  the  elimination  of  nitrogen  in 
starvation  is  less  in  fat  than  in  lean  individuals.  For  instance, 
only  9  grms.  of  urea  were  voided  in  twenty-four  hours  during  the 
later  stages  of  starvation  by  a  well-nourished  and  fat  person  suffer- 
ing from  disease  of  the  brain,  while  J.  Muhk  found  that  20-29 
grms.  urea  were  voided  daily  by  Cetti,  who  had  been  poorly  fed. 

Like  the  destruction  of  proteids  during  starvation,  the  decom- 
position of  fat  proceeds  uninterruptedly.  The  decomposition  of 
fat  does  not  show  so  great  and  rapid  a  decrease  in  the  first  days  of 


446  PHYSIOLOOIGAL  CEEMISTRT. 

starvation  as  the  destruction  of  proteids.  Pettenkofer  and 
VoiT  found,  for  instance,  in  a  starving  dog  the  following  losses  of 
proteids  and  fat  from  the  body  on  different  days  of  starvation: 

TABLE  II. 


Day. 

Weight  of  Body 
iu  Kilos. 

Loss  in 
Flesh.            Fat. 

Oxygen 
absorbed. 

2 

33.9 

341                86 

, , 

5 

31.7 

167            103 
138              99 

358 

8  

30.5 

333 

The  consumption  of  fat  on  the  second  day,  when  the  decom- 
position of  proteids  was  considerable,  was  indeed  less  than  in  the 
following  days.  The  conditions  for  the  destruction  of  proteids  in 
the  animal  body  seem,  as  Voit  has  suggested,  to  be  different  from 
those  for  the  consumption  of  fat. 

The  constant  decrease  in  the  consumption  of  the  adipose  tissue 
and  proteids  during  starvation  must  also  cause  a  decrease  in  the 
extent  of  the  exchange  of  gas  ;  for  instance,  a  diminished  taking 
up  of  oxygen  and  a  diminished  elimination  of  carbon  dioxide. 
This  is  found  to  be  true.  In  starvation  experiments  made  on  a 
cat,  Schmidt  found  that  the  results  for  the  carbon  dioxide  and 
oxygen  fell  in  the  course  of  eighteen  days  from  50.96  grms.  carbon 
dioxide  and  46.20  grms.  oxygen  on  the  first  day  of  starvation  to 
22.26  grms.  carbon  dioxide  and  22.12  grms.  oxygen  on  the  last  day. 
Investigations  on  the  extent  of  exchange  of  gas  in  human  beings  in 
the  starving  condition  were  made  by  Lehmani?"  and  ZuifTZ  on 
Cetti,  who  only  partook  of  water  for  ten  days.  These  investi- 
gators found  that  the  absolute  extent  of  exchange  of  gas  during 
hunger  decreases,  but  that  when  the  oxygen  consumed  and  the 
carbon  dioxide  eliminated  were  calculated  on  the  unit  of  the  weight 
of  the  body — 1  kilo — its  amount  quickly  sinks  to  a  minimum,  but 
then  remains  unchanged  or  may  perhaps  rise  during  the  course  of 
the  fast.  They  found  a  consumption  of  4.65  c.  c.  oxygen  per 
minute  for  1  kilo  during  the  third  to  sixth  day  and  4.73  c.  c.  during 
the  ninth  to  eleventh  day.  It  is  also  a  well-known  fact  that  the 
temperature  of  the  body  of  starving  animals  remains  tolerably  con- 
stant, without  showing  a  mentionable  decrease,  during  the  greater 


EXCHANGE  OF  MATERIAL.  447 

part  of  the.  starvation  period.     The  heat  of  the  animal  sinks  only  a 

few  days  before  death,  and  at  about  33°  to  30°  C.  death  results. 

If  the  carbon  is  burnt   with  oxygen  into  carbon   dioxide,  the 

carbon  dioxide  produced  occupies  the  same  volume  as  the  oxygen 

CO 
consumed,  and  the  quotient  -^  is  therefore  1.     The  same  is  true 

of  the  burning  of  the  carbohydrates,  which  contain  in  themselves 

the  necessary  quantity  of  oxygen  to  oxidize  the  hydrogen,  and  only 

the  quantity  of  oxygen  required  to  oxidize  the  carbon  is  necessary 

to  be  taken  up  for  the  burning  of  the  carbohydrates  into  COg  and 

HjO.     In  the  burning  of  fats  and  proteids  this  is  different.     In 

these  cases  an  absorption  of  oxygen  is  necessary  not  only  for  the 

burning  of  tlie  carbon  but  also  for  the  hydrogen,  and  the  volume  of 

the  carbon  dioxide  formed  is   therefore  smaller  than  the  oxygen 

CO 
consumed.      The  quotient  -~  must  therefore  in  these  cases  be 

smaller  than  1.  The  conditions  are  still  more  complicated  for  the 
proteids,  because  these  bodies  contain  sulphur  which  is  oxidized 
into  sulphuric  acid,  and  also  because  they  are  not  completely  burnt 
in  the  organism,  but  yield  nitrogenized  decomposition  products 
which  contain  hydrogen  and  oxygen  as  well  as  carbon. 

From  the  above  it  follows  that  in  man,  on  a  mixed  diet,  the 
proportion  between  the  inhaled  oxygen  and  the  expired  carbon 
dioxide,  or  the  so-called  I'espiratory  quotient,  must  be  smaller  than  1. 
As  a  rule,  it  is  0.73-0.86  on  a  mixed  diet.  On  feeding  with  an 
exclusively  vegetable  food  rich  in  carbohydrates  it  is  closer  to  1 ; 
with  a  strictly  meat  diet  it  is  lowest,  about  0.7.  In  starvation,  when 
the  person  or  animal  lives  entirely  upon  his  own  body,  it  must  be 
about  the  same  as  when  fed  entirely  upon  meat  and  fat.  As  the 
quotient  for  the  burning  of  proteids  is  0.81-0.75,  and  for  the 
burning  of  fats  0.7,  the  respiratory  quotient  in  starvation  must  be 
in  the  neighborhood  of  0.7.  In  the  above-mentioned  starvation 
experiments  made  by  C.  Schmidt  on  a  cat  it  was  0.765,  while  in  his 
observations  on  Cetti  it  was  still  lower,  or  0.68-0.65. 

Water  passes  uninterruptedly  from  the  body  in  starvation  even 
when  none  is  given.  If  the  amount  of  water  in  the  tissues  rich  in 
proteids  is  considered  as  70-80^,  and  the  amount  of  proteids  in 
the  same  20j^,  then  for  each  gramme  of  destroyed  proteids  about 


448  PHTSIOLOGIGAL  CHEMISTRY. 

4  grammes  of  water  are  set  free.  A  special  increase  in  the  demand 
for  water  does  not  seem  to  occur  in  starving  animals. 

The  mineral  substances  leave  the  body  uninterruptedly  in  starva- 
tion until  death,  and  the  influence  of  the  destruction  of  tissues  is 
plainly  perceptible  by  their  elimination.  Because  of  the  destruction 
of  tissues  rich  in  potassium,  the  proportion  between  potassium  and 
sodium  in  the  urine  changes  in  starvation  so  that,  contrary  to 
the  normal  conditions,  the  potassium  is  eliminated  in  proportion- 
ally greater  quantities.  Mukk  also  observed  in  Cetti's  case  a 
relative  increase  in  the  phosphoric  acid  and  calcium  in  the  urine 
during  starvation,  which  was  due  to  an  increased  exchange  of  bone- 
substance. 

The  question  as  to  the  participation  of  the  different  organs  in 
the  loss  of  weight  of  the  body  during  starvation  is  of  special 
interest.  To  illustrate  this  question  we  will  give  below  the  results 
of  Chossat's  experiments  on  pigeons  and  those  of  VoiT  on  a  male 
cat.  The  results  are  percentages  of  weight  lost  from  the  original 
weight  of  the  organ. 

TABLE  III. 

Pigeon  (Chossat).    Male  Cat  (Voit). 

Fat 93  per  cent.  97  per  cent. 

Spleen 71  "  67  "       ' 

Pancreas 64  "  17  " 

Liver 52  "  54  " 

Heart 45  "  3  " 

Intestines 42  "  18  " 

Muscles 42  "  31 

Testicles 40  " 

Skin 33  "  21  " 

Kidneys 32  "  26  " 

Lungs 22  "  18 

Bones 17  "  14 

Nervous  sytslem..     2  "  3  " 

The  total  quantity  of  blood,  as  well  as  the  amount  of  solids  con- 
tained therein,  decreases,  as  Panum  has  shown,  in  the  same  pro- 
portion as  the  weight  of  the  body.  The  statements  in  regard  to 
the  loss  of  water  by  different  organs  is  somewhat  contradictory  ; 
according  to  Lukjakow,  it  seems  that  the  various  organs  act  some- 
what differently  in  this  respect. 

Tlie  above-tabulated  results  cannot  serve  as  a  measure  of  the 


EXCHANGE  OF  MATERIAL.  449 

exchange  of  material  iu  the  various  organs  during  starvation.  For 
instance,  the  nervous  system  only  shows  a  small  loss  of  weight  as 
compared  to  the  other  organs,  but  horn  this  it  must  not  be  con- 
cluded that  the  exchange  of  material  in  this  system  of  organs  is  not 
active.  The  condition  may  be  quite  different  ;  for  one  organ  may 
derive  its  nutriment  during  starvation  from  some  other  organ  and 
exist  at  its  expense.  A  positive  conclusion  cannot  be  drawn  in 
regard  to  the  activity  of  the  excliange  of  material  in  an  organ  from 
tiie  loss  of  weight  of  that  organ  in  starvation. 

II.    Exchange   of   Material  with    Inadequate    Nutrition. 

The  food  may  be  quantitatively  insufficient  and  the  final  result 
is  absolute  inanition.  The  food  may  also  be  qualitatively  insuffi- 
cient, or  as  we  say,  inadequate.  This  occurs  when  any  of  the 
necessary  nutritive  bodies  are  absent  in  the  food,  while  the  others 
occur  in  sufficient  or  perliaps  indeed  in  excessive  amounts. 

Lack  of  loater  in  the  food.  The  quantity  of  water  in  the 
organism  is  greatest  during  foetal  life,  and  tlien  decreases  with, 
increasing  age  (v.  Bezold).  Naturally,  the  amount  differs  in 
various  organs.  Enamel,  being  almost  free,  contains  only  2  p.  m. 
water,  the  teeth  about  100  p.  ra.,  the  fatty  tissues  and  bones 
60-120-150  p.  m.  The  cartilage  with  540-740  p.  m.  is  somewhat 
richer  in  water,  while  the  muscles,  blood,  and  glands  with  750  to 
more  than  800  p.  m.  are  still  richer.  The  quantity  of  water  is  even 
greater  in  the  animal  fluids  (see  preceding  chapter),  and  the  grown 
body  contains  in  all  about  600  p.  m.  water  (Bischoff).  If  we  bear 
in  mind  that  two  thirds  of  the  animal  organism  consists  of  water  \ 
that  water  is  of  the  very  greatest  importance  in  the  normal,  phy- 
sical composition  of  the  tissues  ;  moreover  that  all  flow  of  juices, 
all  exchange  of  substance,  all  supply  of  nutrition,  all  increase  or 
destruction,  and  all  discharge  of  the  products  of  destruction  are 
dependent  upon  the  presence  of  water;  besides  this,  that  by  its 
evaporation  it  is  an  important  regulator  of  the  temperature  of  the 
body, — we  perceive  that  water  must  be  necessary  for  life.  If  the 
loss  of  water  be  not  replaced  by  fresh  supplies  sooner  or  later,, 
the  organism  succumbs. 

Lack  of  mineral  subdances  in   the  food.     We  are  chiefly  in- 


450  PHYSIOLOGICAL    CHEMISTRY. 

debted  to  Liebig  for  showing  that  the  mineral  substances  are  just 
as  necessary  for  the  normal  composition  of  the  tissues  and  organs, 
and  for  the  normal  course  of  the  processes  of  life,  as  the  organic 
constituents  of  the  body.  The  importance  of  the  mineral  constit- 
uents is  evident  from  the  fact  that  there  is  no  animal  tissue  or 
animal  fluid  which  does  not  contain  mineral  substance,  and  also 
from  the  fact  that  certain  tissues  or  elements  of  tissues  contain 
habitually  certain  mineral  substances  and  not  others,  which  ex- 
plains the  unequal  division  of  the  potassium  and  sodium  compounds 
in  the  tissues  and  fluids.  With  the  exception  of  the  skeleton,  which 
contains  about  220  p.  m.  mineral  bodies  (Volkmann),  the  animal 
fluids  or  tissues  are  poor  in  inorganic  constituents,  and  the  quan- 
tity of  such  only  amounts,  as  a  rule,  to  about  10  p.  m.  Of  the  total 
quantity  of  mineral  substances  in  the  organism,  the  greatest  part 
occurs  in  the  skeleton,  830  p.  m.,  and  the  next  greatest  in  the  mus- 
cles, about  100  p.  m.  (VoLKMANisr). 

The  mineral  bodies  seem  to  be  partly  dissolved  in  the  fluids  and 
partly  combined  with  organic  substances.  In  accordance  with  this 
the  organism  persistently  retains,  with  food  poor  in  salts,  a  part  of 
the  mineral  substances,  also  such  as  are  soluble,  as  the  chlorides. 
On  the  burning  of  the  organic  substances  the  mineral  bodies  com- 
bined therewith  are  set  free  and  are  eliminated.  It  is  also  ad- 
mitted that  they  in  part  combine  with  the  new  products  of  the 
burning,  and  also  that  they  in  part  are  attached  to  organic  nutri- 
tive bodies  absorbed  from  the  intestinal  canal  which  are  poor  in 
salts,  or  nearly  salt-free,  and  are  thus  retained  (Voit,  Foestee). 

If  this  statement  be  correct,  it  is  possible  that  a  constant  supply 
of  mineral  substances  with  the  food  is  not  absolutely  necessary,  and 
that  the  amount  of  inorganic  bodies  Avhich  must  be  administered 
is  insignificant.  The  question  whether  this  be  so  or  not  has  not, 
especially  in  man,  been  sufficiently  investigated;  but  generally  we 
consider  the  need  of  mineral  substances  by  man  as  very  small.  It 
may,  however,  be  assumed  that  man  usually  takes  with  his  food  a 
considerable  excess  of  mineral  substances. 

Investigations  on  animals  in  regard  to  the  action  of  an  insufficient 
supply  of  mineral  substances  with  the  food  have  been  made  by  sev- 
eral investigators,  especially  Eoestee.  He  observed,  on  experiment- 
ing on  dogs  and  pigeons,  with  food  as  poor  as  possible  in  mineral  sub- 


EXCHANGE  OF  MATERIAL.  451 

stances,  a  very  suggestive  disturbance  of  the  functions  of  the  organs, 
especially  the  muscles  and  the  nervous  system,  and  death  resulted 
after  a  time,  indeed  earlier  than  in  complete  starvation.  In  opposi- 
tion to  these  observations  Bunge  has  suggested  that  the  early  death 
in  these  cases  was  not  caused  by  the  lack  of  mineral  salts,  but  more 
likely  by  the  lack  of  bases  necessary  to  neutralize  the  sulphuric 
acid  formed  in  the  burning  of  the  proteids  in  the  organism,  which 
must  be  then  taken  from  the  tissues.  In  accordance  with  this  view, 
BuNGE  and  Lunin  also  found  on  experimenting  on  mice  that  ani- 
mals which  received  nearly  ash-free  food  with  the  addition  of 
sodium  carbonate  were  kept  alive  twice  as  long  as  animals  which 
had  the  same  food  without  the  addition  of  sodium  carbonate.  Spe- 
cial experiments  also  show  that  the  carbonate  cannot  be  replaced 
by  an  equivalent  amount  of  sodium  chloride,  and  that  to  all  appear- 
ances it  acts  by  combining  with  the  acids  formed  in  the  body.  The 
addition  of  alkali  carbonate  to  the  otherwise  nearly  ash-free  food 
may  indeed  delay  death,  but  cannot  prevent  it,  and  even  in  the 
presence  of  the  necessary  amount  of  bases  death  results  for  lack  of 
mineral  substances  in  the  food. 

In  the  above  series  of  experiments  made  by  Bukge  the  food  of 
the  animal  consisted  of  casein,  milk-fat,  and  cane-sugar.  While 
milk  alone  was  an  adequate  and  sufficient  food  for  the  animal, 
Bun^ge  found  that  the  animal  could  not  be  kept  alive  longer  by 
food  consisting  of  the  above  constituents  of  milk  and  cane-sugar, 
with  the  addition  of  all  the  mineral  substances  of  milk,  than  with 
the  food  mentioned  in  the  above  experiments  with  the  addition  of 
alkali  carbonate.  The  question  whether  this  result  is  to  be  ex- 
plained by  the  fact  that  the  mineral  bodies  of  milk  are  chemically 
combined  with  the  organic  constituents  of  the  same  and  can  be 
assimilated  only  in  such  combinations,  or  whether  it  depends  on 
other  conditions,  Bunge  leaves  undecided.  These  observations, 
however,  show  how  difficult  it  is  to  draw  positive  conclusions  from 
experiments  made  thus  far  with  food  poor  in  salts.  Further  investi- 
gations on  this  subject  seem  to  be  necessary. 

With  an  insufficient  supply  of  chlorides  with  the  food  the  elimi- 
nation of  chlorine  by  the  urine  decreases  constantly,  and  at  last  it 
may  stop  entirely  while  the  tissues  still  persistenly  retain  the  chlo- 
rides.    These  last  are,  at  least  in  part,  combined  in  the  body  with 


452  PHYSIOLOGICAL   CHEMISTRY. 

the  organic  substances  which  retain  them.  The  great  importance 
of  such  a  retention  of  chlorides  by  the  tissues  is  apparent  if  we  bear 
in  mind  that  the  NaCl  is  not  only  a  solvent  for  certain  albuminous 
bodies,  or  a  material  for  the  elaboration  of  the  gastric  juice,  but 
that  it  is  also  of  the  greatest  importance  as  a  so-called  indifferent 
salt  for  the  preservation  of  the  normal  consistency  and  the  physio- 
logical imbibition  relation  of  the  tissues. 

If  there  be  a  lack  of  sodium  as  compared  to  potassium,  also  if 
there  be  an  excess  of  potassium  compounds  in  any  other  form  than 
KCl,  the  potassium  combinations  are  replaced  in  the  organism  by 
NaCl,  so  that  new  potassium  and  sodium  compounds  are  produced 
which  are  voided  with  the  urine.  The  organism  becomes  poorer  in 
NaCl,  which  therefore  must  be  taken  in  greater  amounts  from  the 
outside  (Bunge).  This  occurs  habitually  in  herbivora,  and  in  man 
with  vegetable  food  rich  in  potash.  For  human  beings,  and 
especially  for  the  poorer  classes  of  people  who  live  chiefly  on  pota- 
toes and  foods  rich  in  potash,  common  salt  is,  under  these  circum- 
stances, not  only  a  condiment,  but  a  necessary  addition  to  the  food 
(Bunge). 

Lack  of  alkali  carbonates  or  bases  in  the  food.  The  chemical 
processes  in  the  organism  are  dependent  upon  the  presence  of 
alkaline-reacting  tissue-fluids,  whose  alkaline  reaction  is  due  to 
alkali  carbonates.  The  alkali  carbonates  are  also  of  great  impor- 
tance not  only  as  a  solvent  for  certain  albuminous  bodies  and  as 
constituents  of  certain  secretions,  as  of  the  pancreatic  and  intes- 
tinal Juices,  but  they  are  also  a  means  of  transportation  of  the 
carbon  dioxide  in  the  blood.  lb  is  therefore  easy  to  understand 
that  a  decrease  below  a  certain  point  in  the  quantity  of  alkali  car- 
bonate must  endanger  life.  Such  a  decrease  not  only  occurs  with 
lack  of  bases  in  the  food  which  accelerates  death  by  a  relatively  too 
great  production  of  acids  by  the  burning  of  the  proteids  (see  above: 
BuNGE  and  Lunin),  but  it  also  occurs  when  an  animal  is  given 
dilute  mineral  acids  for  a  certain  time.  In  herbivora  the  fixed 
alkalies  of  the  tissues  combine  with  the  mineral  acids,  and  the 
animal  succumbs  after  a  time.  In  carnivora  the  bases  of  the  tis- 
sues are  obstinately  retained;  the  mineral  acids  unite  with  the 
ammonia  produced  by  the  decomposition  of  the  proteids  or  their 


EXCHANGE  OF  MATERIAL.  453 

"splitting  products,  and  carnivora  can  therefore  be  kept  alive  for  a 
longer  time. 

Lack  of  earthy  phosphates.  With  the  exception  of  the  impor- 
tance of  the  alkaline  earths  as  carbonates  and  principally  as  phos- 
phates in  the  physical  composition  of  certain  structures,  such  as 
the  bones  and  teeth,  their  physiological  importance  is  nearly  un- 
known. The  action  which  an  insufficient  supply  of  alkali-earths 
with  the  food  causes  is  connected  with  the  interesting  question  as 
to  the  effect  of  this  lack  upon  the  bony  structure.  This  action,  as 
well  as  the  various  results  obtained  by  experiments  on  young  and 
old  animals,  has  already  been  spoken  of  in  Chap.  VIII,  to  which  we 
refer  the  reader. 

Lack  of  iron.  As  iron  is  an  integral  constituent  of  haemoglobin, 
indispensable  for  the  introduction  of  oxygen,  so  also  it  is  an  indis- 
pensable constituent  of  the  food.  In  iron  starvation  iron  is  con- 
tinually eliminated,  even  though  in  diminished  amounts  (Ham- 
BUEGEE,  DiETL,  V,  Hosslin).  From  the  observations  of  v. 
HossLiK  on  dogs  it  also  seems  that  an  inadequate  supply  of  iron 
with  the  food  causes  an  insufficient  formation  of  haemoglobin.  A 
special  result  of  the  lack  of  iron  is  chlorosis,  which  the  physician 
has  often  to  contend  with  and  whose  oiigin  is  not  really  a  lack  of 
iron  in  the  food,  but  more  likely  an  incomplete  absorption  of  the 
foods  containing  iron  (Bunge).  The  iron-salts  seem  not  to  be  ab- 
sorbed at  all  in  the  intestinal  canal,  or  only  to  a  very  small  extent, 
so  that  it  is  questionable  whether  their  absorption  has  any  men- 
tionable  importance.  It  seems  more  probable  that  the  absorption 
of  iron  from  the  food  takes  place  in  the  form  of  protein  bodies 
(nucleoalbumin)  containing  iron  (Bunge);  and  the  importance  of 
the  iron-salts  in  preventing  the  lack  of  haemoglobin  consists  chiefly, 
according  to  Bunge,  in  that  these  salts  counteract  the  decomposi- 
tion in  the  intestines  of  the  protein  bodies  containing  iron,  which 
split  off  iron  as  iron  sulphide. 

In  the  absence  of  proteid  bodies  in  the  food  the  organism  must 
nourish  itself  by  its  own  proteid  substances,  and  on  such  nutrition 
it  must  earlier  or  later  succumb.  By  the  exclusive  administration 
of  fat  and  carbohydrates  the  consumption  of  proteids  in  these  cases 
is  reduced,  for  by  an  exclusive  fat  and  carbohydrate  diet  the 
metabolism  of  proteids  may  indeed  be  smaller  than  in  complete 


454  PHTSIOLOQICAL   CHEMI8TRT. 

starvation  (Hirschfeld).  In  conformity  with  this  the  animal 
may  be  kept  alive  longer  by  food  containing  only  non-nitrogenized 
bodies  than  in  complete  starvation. 

The  absence  of  fats  and  carbohydrates  in  the  food  affect  car- 
nivora  and  herbivora  somewhat  differently.  It  is  unknown  whether 
carnivora  can  be  kept  alive  for  any  length  of  time  by  food  en- 
tirely free  from  fat  and  carbohydrates.  But  it  has  been  positively 
demonstrated  that  they  cannot  only  be  kept  alive  by  feeding  entirely 
with  meat  freed  as  much  as  possible  from  visible  fat,  but  that  flesh, 
and  perhaps  also  fat,  is  deposited.  Men  or  herbivora,  on  the  con- 
trary, cannot  live  for  any  length  of  time  on  such  food.  On  one 
side  they  lose  the  property  of  digesting  and  assimilating  the  neces- 
sarily large  amounts  of  meat,  and  on  the  other  a  distaste  for  large 
quantities  of  meat  or  proteids  soon  appears. 

III.   Exchange  of  Material  with  Various  Foods. 

For  the  carnivora,  as  above  stated,  meat  as  poor  as  possible  in 
fat  may  be  a  complete  and  suflBcient  food.  As  the  proteids  more- 
over take  a  special  place  among  the  organic  nutritive  bodies  by  the 
quantity  of  nitrogen  they  contain,  it  is  proper  that  we  first 
describe  the  exchange  of  material  with  an  entirely  meat  diet. 

Exchange  of  material  with  food  rich  in  proteids,  or  feeding  only 
with  meat  as  poor  in  fat  as  possible. 

By  an  increased  supply  of  proteids  the  metabolization  of  pro- 
teids and  the  elimination  of  nitrogen  is  increased  and  indeed  in 
proportion  to  the  supply  of  proteids. 

If  a  certain  quantity  of  meat  is  given  as  food  daily  to  carnivora 
and  the  ration  of  meat  is  suddenly  increased,  an  increased  metab- 
olism of  proteids  or  an  increase  in  the  quantity  of  nitrogen  elim- 
inated is  the  result.  If  we  feed  the  animal  daily  for  a  certain  time 
with  larger  quantities  of  the  same  meat,  we  find  that  a  part  of  the 
proteids  accumulates  in  the  body,  but  this  part  decreases  from  day 
to  day,  while  there  is  a  corresponding  daily  increase  in  the  elimina- 
tion of  nitrogen.  In  this  way  a  nitrogenous  equilibrium  is  estab- 
lished, that  is,  the  total  quantity  of  nitrogen  eliminated  is  equal  to 
the  quantity  of  nitrogen  in  the  absorbed  proteids  or  meat.  If,  on 
the  contrary,  an  animal  which  is  in  nitrogenous  equilibrium  iiaving 


EXCHANGE  OF  MATERIAL.  455 

been  fed  on  large  quantities  of  meat  is  suddenly  fed  with  a  small 
quantity  of  meat  per  day,  then  the  animal  gives  up  its  own  bodily 
proteids,  the  amount  decreasing  from  day  to  day.  The  elimination 
of  nitrogen  and  the  metabolism  of  proteids  decrease  constantly,  and 
the  animal  may  in  this  case  also  pass  into  nitrogenous  equilibrium 
or  nearly  into  this  condition.  These  conditions  are  illustrated  by 
the  following  table  (Voit)  : 

TABLE   IV. 

Grms.  of  Flesh  in  the  Food  per  Day. 

Before  the  Test.       During  the  Test. 

1 500  1500 

2 1500  1000 

Grms.  of  Flesh  metabolized  in  Body  per  Day. 

12  3  4  5  6  ? 

1222        1310        1390        1410        1440        1450        1500 
1153        1086        1088        1080        1027 

In  the  first  case  (1)  the  metabolism  of  flesh  before  the  beginning 
of  the  actual  experiment  on  feeding  with  500  grms.  meat  was  447 
grms.,  and  it  increased  considerably  on  the  first  day  of  the  experi- 
ment, after  feeding  on  1500  grms.  meat.  In  the  second  case  (2), 
in  which  the  animal  was  previously  in  nitrogenous  equilibrium 
with  1500  grms.  meat,  the  metabolism  of  flesh  on  the  first  day  of 
the  experiment,  with  only  1000  grms.  meat,  decreased  considerably, 
and  on  the  fifth  day  a  nearly  nitrogenous  equilibrium  was  obtained. 
During  this  time  the  animal  gave  up  daily  some  of  its  own  proteids. 
Between  that  point  below  which  the  animal  loses  from  its  own 
weight  and  the  ma.ximum,  which  seems  to  be  dependent  upon  the 
digestive  and  assimilative  capacity  of  the  intestinal  canal,  car- 
nivora  may  be  kept  in  a  nitrogenous  equilibrium  with  a  varying 
quantity  of  proteids  in  the  food. 

The  supply  of  proteids,  as  well  as  the  condition  of  the  body, 
affects  the  extent  of  the  proteid  metabolism.  A  body  which  has 
become  rich  in  proteids  by  a  previous  abundant  meat  diet  must,  to 
prevent  a  loss  of  proteids,  take  up  more  proteid  with  the  food  than 
a  body  poor  in  proteids.  The  quantity  of  fat  in  the  body  also  has 
a  great  influence.     As  the  fat  of  the  body  lowers  the  disintegration 


456  PHYSIOLOGICAL   CHEMISTRY. 

of  proteids  in  starvation,  so  also  it  diminishes  the  disintegration  of 
the  proteids  taken  with  the  food. 

Pettenkofer  and  Voit  have  made  investigations  on  the  metab- 
olism of  fat  with,  an  exdusively  albuminous  diet.  These  investi- 
gations have  shown  that  by  increasing  the  quantity  of  proteids  in 
the  food  the  daily  metabolism  of  fat  decreases,  so  that  indeed  a 
formation  of  fat  from  proteids,  or  more  correctly  an  excess  of  car- 
hon  in  the  food  as  compared  to  the  excretions,  is  produced,  and 
this  excess  is  considered  as  indicating  a  formation  of  fat  from  pro- 
teids. To  illustrate  this  the  following  series  of  experiments  were 
made  on  dogs,  which  were  fed  during  seven  different  periods  with 
increasing  quantities  of  meat.  Here  as  well  as  in  the  following 
pages  the  signs  +  and  —  represent  an  increase  or  a  loss  of  the  sub- 
stances under  consideration. 


TABLE 

V. 

Flesh 

Flesh 

Fat 

3iven. 

Decomposed . 

on 

the  Body. 

165 

-  165 

-  95 

'566 

599 

-    99 

-47 

1000 

1079 

-    79 

-19 

1500 

1500 

'' 

+   4 

1800 

1757 

+  ■43 

+    1 

2000 

2044 

-    44 

+  58 

2500 

2512 

-    12 

+  57 

In  these  cases,  according  to  the  generally-received  opinion,  a 
formation  of  fat  from  proteids  has  taken  place,  even  though  it  is 
small  as  compared  to  the  quantity  of  decomposed  proteid.  In  this 
formation  of  fat  the  proteids  of  the  organism  split  into  a  nitrogen- 
ized  part  which  ultimately  yields  urea,  uric  acid,  etc.,  and  a  non- 
nitrogenized  part  which  passes  into  fat  or  fat-forming  substances. 
This  non-nitrogenized  part  first  diminishes  the  metabolism  of  fat 
and  then,  when  it  is  formed  in  greater  quantities,  it  is  stored  up  as 
adipose  tissue. 

The  accumulation  of  fat  in  the  body  is  therefore  only  small 
■with  an  exclusively  meat  diet.  The  same  is  true  also  of  the  storing 
up  of  proteids,  which  decreases  from  day  to  day  and  which  only 
lasts  for  a  short  time,  because  nitrogenous  equilibrium  soon  occurs. 
This  is  also  the  reason  why  with  an  exclusively  meat  diet  a  well- 


EXCHANGE  OF  MATERIAL.  457 

nourished   body  can    be   kept  in    its  ordinary  condition,  while   a 
poorly-nourished  or  diseased  organism  cannot  be  made  fat. 

The  very  considerable  elimination  of  nitrogen  and  the  peculiar- 
ities which  it  presents  in  an  exclusively  meat  diet  have,  together 
with  other  circumstances,  among  which  is  the  unequal  behavior  of 
the  metabolism  of  proteids  on  the  first  and  the  following  days  of 
starvation,  led  to  the  view  (Voit)  that  all  proteids  in  the  body  are 
not  decomposed  with  the  same  ease.  Vott  differentiates  the  proteids 
fixed  in  the  tissue-elements,  so-called  organized  proteids,  tissue- 
profeids,  from  those  proteids  wiiich  circulate  with  the  fluids  in  the 
body  and  its  tissues  and  which  are  taken  up  by  the  living  cells  of 
the  tissues  from  the  interstial  fluids  washing  them.  These  circu- 
lating proteids  are,  according  to  Voit,  more  easily  and  quickly 
destroyed  than  the  tissue-proteids.  Although  in  a  fasting  animal 
which  has  been  previously  fed  with  meat  an  abundant  and  quickly- 
decreasing  decomposition  of  proteids  takes  place,  Avhile  in  the  fur- 
ther course  of  starvation  this  proteid  metabolism  becomes  less  and 
more  uniform,  still  this  depends  upon  the  fact  that  the  supply  of 
circulating  proteids  is  diminished  chiefly  in  the  first  days  of  starva- 
tion and  the  tissue-proteids  in  the  last  days. 

The  tissue-elements  constitute  an  apparatus  of  a  relatively  stable 
nature,  which  has  the  power  of  taking  proteids  from  the  fluids 
washing  the  tissues  and  digesting  them,  while  a  few  proteids,  the 
tissue-proteids,  are  ordinarily  only  disoi-ganized  to  a  small  extent, 
about  Ifo  daily  (Voit).  By  an  increased  supply  of  proteids  the 
activity  of  the  cells  and  their  ability  to  decompose  nutritive  pro- 
teids is  also  increased  to  a  certain  degree.  When  nitrogenous 
equilibrium  is  obtained  after  increased  supply  of  proteids,  it  denotes 
that  the  decomposing  power  of  the  cells  for  proteids  has  increased 
so  that  the  same  amount  of  proteids  is  metabolized  as  is  supplied 
to  the  body.  If  the  proteid  metabolism  is  decreased  by  the  simul- 
taneous administration  of  other  non-nitrogenized  foods  (see  below), 
a  part  of  the  circulating  proteids  may  have  time  to  become  fixed 
and  organized  by  the  tissues,  and  in  this  way  the  mass  of  the  flesh 
of  the  body  increases.  During  starvation  or  with  lack  of  proteids 
in  the  food  the  reverse  takes  place,  for  a  part  of  the  tissue  proteids 
is  converted  into  circulating  proteids  which  are  metabolized,  and 
in  this  case  the  flesh  of  the  body  decreases. 


458  PHYSIOLOGICAL   CHEMISTRY. 

Voit's  doctrine  of  the  circulating  and  tissue  proteids  is  indeed  a 
hypottiesis,  but  it  explains  in  a  satisfactory  manner  a  number  of 
otherwise  very  intricate  relations  and  it  agrees  best  with  the  facts. 
This  theory  has  received  further  confirmation  from  the  investiga- 
tions of  several  others,  as  Panum,  Falck  and  Feder,  on  the  tem- 
porary secretion  of  urea  after  food  rich  in  proteids.  From  the 
investigations  on  a  dog  it  was  found  that  the  secretion  of  urea 
increases  almost  immediately  after  a  meal  rich  in  proteids,  and  that 
it  reaches  its  maximum  in  about  six  hours,  when  about  one  half  of 
the  administered  proteids  is  secreted  as  the  corresponding  quantity 
of  urea.  If  we  also  recollect  that,  according  to  an  observation  of 
ScHMiDT-MiJLHEiM  on  a  dog,  about  33^  of  the  given  proteids  are 
absorbed  in  the  first  two  hours  after  the  meal  and  about  56^  in  the 
course  of  the  first  six  hours,  we  may  then  infer  that  the  increased 
elimination  of  nitrogen  after  a  meal  is  due  to  a  metabolization  of 
the  digested  and  absorbed  proteids  of  the  food.  If  we  admit  that 
the  destroyed  proteid  must  have  been  organized,  then  the  greatly 
increased  elimination  of  nitrogen  after  a  meal  rich  in  proteids  sup- 
poses a  far  more  rapid  and  comprehensive  destruction  and  recon- 
struction of  the  tissues  than  has  been  generally  admitted. 

Voit's  theory  on  the  different  behavior  of  the  tissue  proteids 
and  the  circulating  proteids  in  the  animal  body  seems  to  have 
found  support  in  the  investigations  of  Ludwig  and  Tschirjew  and 
of  FoRSTER.  In  TscHiRJEw's  experiments  a  dog  was  given  at  one 
time  boiled  dog's  blood,  and  at  another  time  the  same  quantity  of 
defibrinated  dog's  blood  was  injected  into  a  vein.  In  the  latter  case 
the  secretion  of  urea  was  very  little  increased,  while  in  the  former 
case  it  increased  proportionally  to  the  food  consumed.  In  Fors- 
ter's  experiments,  on  the  contrary,  a  dog  was  transfused  with 
defibrinated  dog's  blood  and  also  with  horse-  or  dog-blood  serum. 
After  the  transfusion  of  the  blood  the  secretion  of  nitrogen  was 
somewhat  greater  than  in  starvation,  but  the  increase  was  only 
inconsiderable.  In  two  experiments,  in  which  395  and  611  grms. 
of  blood  were  transfused,  the  increase  was  only  3.6  and  3.4  grms. 
urea,  while  the  proteids  contained  in  the  transfused  blood  corre- 
sponded to  32  and  42  grms.  urea.  After  the  tranf usion  of  522  grms. 
of  dog's-blood  serum,  in  which  the  quantity  of  proteids  corre- 
sponded to  10.6  grms.  urea,  the  elimination  of  urea  was  only  6.4 


EXCHANGE  OF  MATERIAL.  459 

grms.  greater  on  the  day  of  the  transfusion  than  on  the  following 
day.  According  to  these  experiments,  the  proteids  of  the  blood  - 
corpuscles,  which  are  considered  as  tissue-proteids,  are  less  easily 
metabolized  than  digested  blood-proteids  or  the  proteids  of  the 
blood-serum,  and  therefore  these  experiments  confirm  Voit's 
views. 

It  has  been  stated  above  that  other  foods  may  decrease  the 
destruction  of  proteids.  Gelatine  is  such  a  food.  Gelatine  and  the 
gelatine-formers  do  not  seem  to  be  converted  into  proteid  in  the 
body,  and  this  last  cannot  be  entirely  replaced  by  gelatine  in  the 
food.  For  example,  if  a  dog  is  fed  on  gelatine  and  fat,  its  body 
sustains  a  loss  of  proteids  even  when  the  quantity  of  gelatine  is  so 
large  that  the  animal,  with  an  amount  of  fat  and  meat  containing 
just  the  same  quantity  of  nitrogen  as  the  gelatine  in  question,  may 
remain  in  nitrogenous  equilibrium.  On  the  contrary,  gelatine,  as 
VoiT,  Panum  and  Oeeum  have  shown,  has  a  great  value  as  a  means 
of  sparing  the  proteids,  and,  according  to  Voit,  it  may  decrease  the 
decomposition  of  proteids  to  a  still  greater  extent  than  fats  and 
carbohydrates.  This  is  apparent  from  the  following  summary  of 
Voit's  experiments  on  a  dog  : 

TABLE  VI. 

Food  per  Day.  Flesh. 


Meat.  Gelatine.  Fat.  Sugar,  Decomposed.  On  the  Body. 

400  0  200  0                     450              -  50 

400  0           0  250                  439              -  39 

400  200         0  0                    256             +  44 

This  ability  of  gelatine  to  spare  the  proteids  is  explained  by 
Voit  by  the  statement  that  the  gelatine  is  decomposed  instead  of  a 
part  of  the  circulating  proteids,  whereby  a  part  of  this  last  may  be 
organized. 

Gelatine  may  also  decrease  somewhat  the  consumption  of  fat, 
although  it  is  of  less  value  in  this  respect  than  the  carbohydrates. 

The  question  of  nutritive  value  of  peptones  stands  in  close  rela- 
tion to  the  nutritive  value  of  the  proteids  and  gelatine.  The  early 
investigations  made  by  Maly,  Plos'z  and  Gyergyay,  and  Adam- 
KiEwric'z  have  led  to  the  conclusion  that  an  animal  with  food  which 


460  PHT8I0L0OICAL  CHEMISTRY. 

contains  no  proteids  besides  peptones  may  not  only  preserve  its 
nitrogenous  equilibrium,  but  indeed  its  proteid  condition  may  in- 
crease. In  opposition  to  this  VoiT  believes,  basing  his^opinion  upon 
soine  recent  experiments  conducted  by  Feder,  that  the  peptones  are 
completely  destroyed  in  the  body;  that  indeed  by  their  ability  of 
sparing  the  proteids  they  entirely,  or  almost  entirely,  prevent  the 
consumption  of  proteids,  but  cannot  pass  into  proteid.  The  gen- 
eral view  is  still  that  (see  page  231)  peptones  are  reconverted  into 
proteids  in  the  body. 

In  the  above-mentioned  experiments  with  peptones  a  mixture  of 
albumoses  and  peptones  in  the  modern  sense  was  used.  Eecently 
ZuNTZ  and  Pollitzer  have  made  experiments  on  dogs  partly  with 
meat  and  partly  with  pure  peptones  and  albumoses  of  various  kinds. 
In  these  experiments  a  deposit  of  proteids  (retention  of  a  part  of 
the  nitrogen)  seems  to  have  taken  place  in  the  body,  and  if  a  cor- 
rection be  made  for  that  nitrogen  which  is  contained  in  the  extrac- 
tive bodies  of  the  meat,  then  the  investigated  digestive  products 
seem  to  have  about  the  same  nutritive  value  for  the  body  as  the 
corresponding  quantity  of  proteids  of  the  meat. 

From  experiments  made  by  Weiske  on  herbivora  it  appears 
that  asparagin  may  spare  albumin  in  such  animals.  In  carnivora 
(J.  Munk)  and  in  mice  (VoiT  and  Politis)  it  was  found  that 
asparagin  does  not  seem  to  have  any  sparing  action  on  the  proteids. 
It  is  not  known  how  it  acts  in  man. 

Exchange  of  Material  on  a  Diet  consisting  of  Proteid  and  Fat. 
Fat  cannot  arrest  or  prevent  the  destruction  of  proteids;  but  it  can 
decrease  it,  and  so  spare  the  proteids.  This  is  apparent  from  the 
following  table  of  VoiT.  A  is  the  average  for  three  days,  and  B  for 
six  days. 

TABLE  VII. 

Food.  Flesh. 


Meat.  Fat.  Metabolized.         On  the  Body. 

A....   1500  0  1512  -  12 

B. .  .  .  1500         150  1474  +  26 

The  adipose  tissue  of  the  body  acts  like  the  food-fat,  and  the 
proteid-sparing  effect  of  the  former  may  be  added  to  that  of  the 
latter,  so  that  a  body  rich  in  fat  may  not  only  remain  in  nitrogenous 


EXCHANGE  OF  MATERIAL.  461 

equilibrium,  but  may  even  add  to  the  store  of  bodily  proteids,  while 
in  a  lean  body  with  food  containing  the  same  amount  of  proteids 
and  fat  there  would  be  a  loss  of  proteids.  In  a  body  rich  in  fat  a 
greater  amount  of  proteids  is  protected  from  metabolism  by  a  cer- 
tain quantity  of  fat  than  in  a  lean  body. 

Because  of  the  sparing  action  of  fats  an  animal  by  the  addition 
of  fat  to  its  food  may,  as  is  apparent  from  the  tables,  increase  its 
proteid  condition  with  a  quantity  of  meat  which  is  insufficient  to 
preserve  nitrogenous  equilibrium.  The  proportion  of  proteids 
and  fats  in  the  food  is  of  the  greatest  importance  in  regard  to  in- 
creasing the  proteids  of  the  body.  With  an  exclusively  proteid  diet 
the  metabolism  of  proteids  increases  with  the  increased  amount 
of  proteids  in  the  food,  and  this  behavior  is  not  prevented  by  the 
addition  of  fat  to  the  food,  even  though  the  absolute  extent  of  the 
metabolism  of  proteids  is  somewhat  diminished.  In  the  presence 
of  a  great  deal  of  proteid  in  pro]3ortion  to  the  fat  of  the  food,  very 
large  quantities  of  proteid  are  necessary  for  the  maintenance  of 
nitrogenous  equilibrium,  as  well  as  for  an  increase  of  proteid,  while 
by  the  addition  of  a  relatively  large  amount  of  fat  to  the  proteids 
such  a  result  is  reached  even  with  comparatively  small  amounts  of 
proteids.     The  following  table  will  elucidate  this  point: 

TABLE  VIII. 

Food.  Flesh. 


Meat.  Fat.  Metabolized.  On  the  Body. 

450  250                    344  +  106 

1000  250                    875  +  135 

1500  250                   1381  +  119 

The  table  shows  that  also  in  the  presence  of  fat  the  proteid  de- 
struction decreases  with  increased  amounts  of  proteids  in  the  food, 
and  that,  because  of  this,  in  the  given  examples  no  essentially  in- 
creased metabolism  of  proteid  is  obtained  with  a  diet  of  1 500  grms. 
meat  and  250  grms.  fat  than  with  450  grms.  meat  and  the  same 
quantity  of  fat.  The  importance  of  this  fact  will  be  spoken  of 
later. 

If  the  quantity  of  meat  in  the  food  is  kept  constant  by  feeding 
with  meat  and  fat,  while  the  fat  varies,  then  the  destruction  of  pro- 


462  PHYSIOLOGICAL   CHEMISTRY. 

teids  may  gradually  decrease  with  increased  quantity  of  fat.  This 
does  not  always  take  place,  but  on  feeding  with  increased  amounts 
of  carbohydrates  it  does  (Voit). 

The  same  sparing  action  on  proteids  which  the  neutral  fats 
have  occurs,  according  to  J.  Munk,  also  with  the  fatty  acids,  while 
the  second  chief  constituent  of  the  neutral  fats,  glycerine,  when  it 
is  taken  in  quantities  equal  to  1-2  grms.  per  kilo  of  the  body  does 
not  seem  to  have  any  influence  on  proteid  metabolism  (J.  Munk). 

In  regard  to  the  metabolism  of  fat,  it  has  been  found  that  with  a 
constant  quantity  of  proteid  in  the  food  the  metabolism  of  fat  in- 
creases with  variable  amounts  of  absorbed  fats.  The  following 
table  seems  to  show  this : 


Food. 

TABLE  IX. 

Fat. 

Meat.       Fat. 
500           0 
500        100 
500       200 

Metabolized.    Oa  the  Body. 

47                 -47 

66                 +34 

109               +  91 

The  fat  of  the  body  acts  like  the  fat  of  the  food.  A  body  rich 
in  fat  decomposes  a  greater  fraction  of  fat  than  a  lean  body,  and 
the  same  quantity  of  absorbed  fat  of  the  food,  which  in  a  fat  body 
is  completely  decomposed,  may  in  a  lean  body  cause  a  deposit  of 
fat.  If  the  body  takes  greater  amounts  of  fat  and  proteids  than  it 
can  decompose  in  the  same  time,  then  with  increasing  amounts  of 
absorbed  fats  the  fraction  of  the  same  which  is  deposited  in  the 
body  also  increases  (see  Table  IX).  The  greatest  deposit  of  pro- 
teids and  fat  occurs  after  taking  medium  quantities  of  both  in 
proper  proportion  to  each  other  (see  below). 

Exchange  of  Material  with  a  Diet  consisting  of  Proteids  and 
Carbohydrates.  That  which  has  been  said  above  in  regard  to  the 
action  of  fats  on  the  metabolism  of  proteids  answers  essentially  also 
for  the  carbohydrates.  The  carbohydrates  may  also  spare  the 
proteids.  By  the  addition  of  carbohydrates  to  the  food  the  carnivora 
not  only  remains  in  nitrogenous  equilibrium,  but  the  same  quantity 
of  meat  which  in  itself  is  insuflBcient  and  which  without  carbo- 
hydrates would  cause  a  loss  of  weight  in  the  body  may  with  the 
addition  of  carbohydrates  produce  a   deposit   of  proteids.     The 


EXCHANOE  OF  MATERIAL.  463 

carbohydrates  liave  a  stronger  sparing  action  on  proteids  than  fats 
(Voit).     This  is  apparent  from  the  following  table  : 


TABLE    X. 

Food. 

Flesh. 

Meat. 

Fat.       Sugar. 

Starch. 

Metabolized.  On  the  Boc 

500 

250 

558 

-    58 

500 

300 

466 

+    34 

500 

200 

505 

-      5 

800 

250 

745 

-f-    55 

800 

200 

773 

+   27 

2000 

200-300 

1792 

+  208 

2000 

250         .' ." '. 

1883 

+  117 

Because  of  the  great  sparing  action  of  carbohydrates  on  the 
proteids,  the  herbivora,  whose  food  generally  contains  large  quanti- 
ties of  carbohydrates,  easily  increase  in  proteids  (Voit). 

While  with  the  same  amount  of  flesh  increased  amounts  of  fat 
in  the  food  do  not  continuously  decrease  the  destruction  of  proteids, 
according  to  Voit  the  carbohydrates  habitually  decrease  the 
metabolism  of  proteids.  This  is  seen  from  the  previous  table,  but 
is  more  apparent  from  the  following  : 


TABLE  XL 

Food. 

Flesh. 

Meat. 

Carbohydrates . 

Metabolized.  On  the  Body. 

500 

100 

537 

-    37 

500 

200 

505 

-      5 

500 

300 

466 

+   34 

2000 

100 

1847 

+  153 

2000 

200 

1778 

+  222 

2000 

200 

1780 

+  220 

With  the  addition  of  carbohydrates  to  the  food  the  destruction 
of  proteids  increases  with  an  increased  amount  of  proteids.  In  the 
presence  of  only  small  amounts  of  carbohydrates  very  large 
amounts  of  proteids  are  necessary  in  the  food  to  produce  an  increase 
in  the  proteids  of  the  body,  while  the  result  is  more  simply  and 
advantageously  attained  by  considerably  less  proteids  and  propor- 
tionally more  carbohydrates. 

The  action  of  the  carbohydrates  on  the  accumulation  of  fat 
has  been  demonstrated  by  the  investigations  of  Voit  and  Pettex- 
KOFER  showing  that  the  carbohydrates  not  only  decrease  tlie 
metabolism  of  fat  and  prevent  its  loss,  but  also  cause  its  accumu- 


464  PHYSIOLOGICAL   CHEMISTRY, 

lation.  The  various  views  in  regard  to  the  importance  of  the 
carbohydrates  in  the  formation  of  fat  which  have  been  suggested 
from  time  to  time  have  been  given  on  page  249,  and  it  is  there 
stated  that,  according  to  the  present  view,  the  carbohydrates  not 
only  spare  the  fat,  but  may  also  be  converted  into  fat  in  the  body. 

The  very  important  question  as  to  the  conditions  for  the  depo- 
sition of  fat  and  flesh  in  the  body,  stands  in  close  relation  to  what 
has  just  been  said  in  regard  to  food  consisting  of  proteids  and 
carbohydrates. 

In  the  previous  pages  it  was  repeatedly  stated  that  an  exclusive 
diet  rich  in  proteids  causes  an  increased  destruction  of  proteids,  and 
that  such  a  diet  soon  produces  a  nitrogenous  equilibrium.  By  the 
exclusive  increased  administration  of  proteids  the  proteid  condition 
of  the  body  may  be  increased  only  for  a  short  time  and  to  a  small 
extent,  and  this  only  when  the  body  was  previously  proportionally 
well  fed.  This  does  not  occur  in  bodies  poor  in  fat  from  disease  or 
from  some  other  cause.  If  we  wish  to  cause  a  deposition  of  pro- 
teids in  the  body,  then  we  must  administer  in  sufficient  amounts 
wibh  the  food,  besides  proteids,  also  other  bodies  which  will  spare 
the  proteids,  such  as  gelatine,  fat,  or  carbohydrates,  and  indeed,  for 
several  reasons,  chiefly  fat  and  carbohydrates. 

It  has  also  been  previously  stated  that,  because  of  the  property 
of  the  proteids  to  raise  the  proteid  metabolism,  an  accumulation  of 
proteids  may  be  caused  more  economically  and  better  with  a  medium 
amount  of  proteids  and  proportionally  more  non-nitrogenized  sub- 
stances than  with  a  greater  amount  of  proteids  and  proportionally 
less  non-nitrogenized  bodies.  Above  all,  such  a  proper' relation 
between  proteids  and  non-nitrogenized  bodies  is  important  when  we 
aim  at  keeping  the  deposit  of  flesh  for  a  longer  time.  The  follow- 
ing  extracts  from  Voit's  tables  are  instructive  in  this  regard  : 


Number  of  Days 

TABLE  XII. 

Food.                rp^fg^j  Depogjt  ^f 

Nitrogenous 

of  Experimentation. 

32 
3 
3 
4 
7 
3 

Meat.grms.    Fat,  grms!     Flesh,  grms.      KquU.bnum. 

500             250               1794             not  yet 
750              250                 271                near 

1000             250                 375 

1500             250                 476 

1800              250                 854    nitrogenous  equilibrium 

2000             250                352               near 

EXCHANGE  OF  MATERIAL.  465 

The  greatest  absolute  deposition  of  flesh  in  the  body  was 
obtained  in  these  cases  with  only  500  grms.  flesh  and  250  grms.  fat, 
and  even  after  32  days  the  nitrogenous  equilibrium  had  not  occurred. 
On  feeding  with  1800  grms.  meat  and  250  grms.  fat  the  nitrogenou3 
equilibrium  occurred  after  7  days  ;  and  though  the  deposition  of 
flesh  per  day  was  greater,  still  the  absolute  deposit  was  not  one  half 
as  great  as  in  the  former  case.  Inasmuch  as  the  quantity  of  pro- 
teids  does  not  decrease  below  a  certain  amount,  it  seems  that  the 
most  abundant  and  most  lasting  deposition  of  flesh  is  obtained  with 
a  food  which  does  not  contain  too  much  proteids  in  proportion  to 
the  fat.  The  same  is  also  true  of  a  diet  consisting  of  proteids  and 
carbohydrates. 

From  the  above  conditions  concerniug  a  deposit  of  fat  in  the 
body  it  follows  that  such  a  deposit  may  indeed  occur  with  an 
exclusively  flesh  diet,  but  that  in  this  case  it  is  only  very  small  even 
when  large  amounts  of  proteids  are  taken.  For  the  production  of 
an  abundant  deposit  of  fat  the  body  must  take  with  the  food,  besides 
proteids,  either  fats  or  carbohydi-ates  or,  which  is  best  for  human 
beings,  fat  and  carbohydrates  simultaneously.  The  carbohydrates 
are  of  special  importance  because  they  are  generally  cheaper  iu 
comparison  with  the  fats.  As  the  non-uitrogenized  bodies  are, 
according  to  all  appearances,  the  most  important  source  of  muscular 
activity,  then  diminished  bodily  work  or  rest  must  be  a  favorable 
condition  for  the  deposition  of  fat  in  the  body.  Rest,  with  a 
proper  combination  of  the  three  chief  groups  of  organic  food,  is 
therefore  of  great  importance  in  fattening,  the  object  being  to 
cause  as  great  an  increase  as  possible  in  the  mass  of  the  proteids 
and  fats  in  the  body  in  the  cheapest  way. 

Action  of  certain  other  Bodies  on  the  Exchange  of  Material. 
Water.  If  a  quantity  in  excess  of  that  wiiich  is  necessary  is  intro- 
duced into  the  organism,  the  excess  is  quickly  and  principally 
eliminated  with  the  urine..  This  increased  elimination  of  urine 
causes  in  fasting  animals  (VoiT,  Forster),  but  not  to  any  mention- 
able  degree  in  animals  taking  food  (Seegen,  Mujstk,  Mayer),  an 
increased  elimination  of  urea.  The  reason  for  this  increased  elimi- 
nation is  sought  for  in  the  fact  that  the  abundant  drinking  of  water 
causes  a  complete  washing  out  of  the  urea  from  the  tissues.  An- 
other view,  which  is  defended  bv  Voit,  is  that  because  of  the  more 


466  PHYSIOLOGICAL   CIIEMISTRT. 

active  current  of  fluids  after  taking  large  quantities  of  water  an 
increased  metabolism  of  proteids  takes  place.  Voit  considers  this 
explanation  is  the  correct  one,  although  he  does  not  deny  that  by 
the  abundant,  administration  of  water  a  more  complete  washing  out 
of  the  urea  from  the  tissues  takes  place. 

In  regard  to  the  action  of  water  on  the  formation  of  fat  and  its 
metabolism,  the  view  that  abundant  drinking  of  water  is  favorable 
for  the  deposition  of  fat  seems  to  be  generally  admitted,  while 
taking  only  very  little  water  acts  against  its  formation. 

Salts.  The  excretion  of  urine,  even  when  no  great  quantities 
of  water  are  taken,  is  increased  by  common  salt,  and  the  elimina- 
tion of  urea  is  also  increased  at  the  same  time.  The  same  two 
possibilities  may  be  considered  for  this  last  as  in  the  action  of  water 
on  the  excretion  of  urea.  The  experiments  continued  for  a  long 
time  by  Voit,  in  which  the  absolute  increase  of  the  elimination  of 
urea  was  considerable  (106  grms.  in  49  days),  render  the  conclusion 
probable  that  common  salt  somewhat  increases  the  metabolism  of 
the  proteids.  Certain  other  salts,  such  as  potassium  chloride, 
sodium  sulphate,  sodium  phosphate,  acetate,  saltpetre,  and 
ammonium  chloride,  also  seem  to  act  like  common  salt.  Sodium 
borate  and  the  sodium  salts  of  salicylic  and  benzoic  acids  also  seem 
to  have  an  increased  action  on  the  metabolism  of  proteids. 

Alcohol.  The  question  as  to  how  far  the  alcohol  absorbed  in  the 
intestinal  canal  is  burnt  in  the  body,  or  whether  it  leaves  the  body 
unchanged  by  various  channels,  has  been  the  subject  of  much  dis- 
cussion. To  all  appearances  the  greatest  part  of  the  alcohol  is  burnt. 
According  to  Bodlander,  1.18^  of  the  alcohol  taken  is  eliminated 
with  the  urine,  0.14^  by  the  evaporation  from  the  skin,  and  1.6^ 
with  the  expired  air.  The  remainder,  or  about  97^,  is  burnt  in  the 
body.  As  the  alcohol  is  in  greatest  part  burnt  in  the  body,  then 
the  question  arises  whether  it  acts  sparingly  on  other  bodies,  and 
whether  it  is  to  be  considered  as  a  nutritive  body.  The  investiga- 
tions made  to  decide  this  question  have  led  to  no  decisive  result. 
In  the  experiments  on  the  elimination  of  nitrogen  in  human  beings 
sometimes  a  diminished  (Hammon^d,  E.  Smith,  Obernier),  some- 
times an  unchanged  (Parkes  and  Wollowicz),  and  in  other  cases 
an  increased  (Forster  and  EoMBYisr')  elimination  of  nitrogen  was 
observed   after  the  administration  of  small  amounts  of  alcohol. 


EXCHANGE  OF  MATERIAL.  467 

FOKKER  and  J.  Munk  after  the  ud ministration  of  small  amounts  of 
alcohol  to  dogs  found,  a  diminislied,  and  after  large  amounts  an 
increased,  metabolism  of  proteids. 

Many  observations  have  been  made  in  regard,  to  the  extent  of 
exchange  of  gas  after  taking  alcoliol.  Boeck  and  Bauer  observed 
in  dogs  after  giving  small  amounts  of  alcohol  that  the  consumption 
of  oxygen  as  well  as  the  elimination  of  carbon  dioxide  was  increased. 
BoDLANDER  found  in  rabbits  and  dogs  a  decrease  in  the  consump- 
tion of  oxygen  and  the  elimination  of  carboji  dioxide,  while  Wol- 
FERS  found  an  increased  consumption  of  oxygen  in  rabbits.  In  an 
investigation  on  the  human  body  Zuntz  and  Berdez,  and  also 
Geppert,  observed  no  essential  change  in  the  respiratory  exciiange 
of  gas  after  small,  non-intoxicating  doses  of  alcohol.  As  alcohol  is 
in  greatest  part  burnt  up  in  the  body  and  the  exchange  of  gas  is 
nevertheless  not  essentially  raised,  it  seems  as  if  the  alcohol  dimin- 
ishes the  combustion  of  other  bodies  and  tiiereby  has  a  sparino- 
value.  This  value  may  still,  if  it  really  has  such  an  action,  be  of 
essential  importance  only  in  certain  cases,  as  large  quantities  of 
alcohol  taken  at  once  or  the  continued  use  of  smaller  quantities  has 
injurious  action  on  the  organism.  Alcohol  may  therefore  be  con- 
sidered as  a  nutritive  body  in  exceptional  cases  only,  and  it  other- 
wise must  be  considered  as  an  article  of  luxury. 

Coffee  and  tea  have  no  positively  proved  action  on  the  exchange 
of  material,  and  their  importance  lies  chiefly  in  their  action  upon 
the  nervous  system. 

IV.   The  Dependence  of  the  Exchange  of  Material  on 
Other  Conditions. 

Rest  and  Work.  According  to  Liebig,  muscular  activity  is  con- 
nected with  an  increased  metabolism  of  proteids,  but,  as  has  been 
mentioned  on  page  267,  the  investigations  of  others,  especially  Voit 
on  dogs,  and  of  Petten-kofer  and  Voit  on  man,  show  that  the 
total  elimination  of  nitrogen  during  activity  or  as  a  result  of  the 
same  is  not  mentionably  increased.  It  is  indeed  true  that  certain 
investigators  have  observed  an  increased  elimination  of  nitrogen  in 
special  cases;  but  this  increase  has  been  explained  in  other  ways. 

Work   may,  for  instance,  when    it   is   connected    with    violent 


468  PHYSIOLOGICAL   CHEMISTBT. 

movements  of  the  body,  easily  cause  dyspnoea,  and  this  last  may,  as 
Fbankel  has  shown,  since  diminution  of  the  oxygen  supply  in- 
creases the  proteid  metabolism,  cause  an  increase  in  the  elimination 
of  nitrogen.  In  other  series  of  experiments  the  quantity  of  carbo- 
hydrates and  fats  in  the  food  was  not  sufficient;  the  supply  of  fat 
in  the  body  was  decreased  thereby,  and  the  destruction  of  proteids 
was  also  correspondingly  increased.  Work  may  also  increase  the 
appetite,  and  an  increase  in  the  elimination  of  nitrogen  may  be 
caused  by  the  greater  quantity  of  proteids  taken.  According  to 
the  generally-accepted  views,  muscular  activity  has  hardly  any  in- 
fluence on  the  metabolism  of  proteids. 

On  the  contrary,  it  has  a  very  considerable  influence  on  tho 
metabolism  of  non-nitrogenized  bodies  and — as  a  measure  of  the 
extent  of  the  metabolism — on  the  elimination  of  carbon  dioxide 
and  the  consumption  of  oxygen.  This  action,  which  was  first 
observed  by  Lavoisier,  has  recently  been  confirmed  by  many  in- 
vestigators. Pettekkofer  and  Voit  have  made  investigations  as 
to  the  metabolism  of  the  nitrogenized  as  well  as  of  the  non- 
nitrogenized  bodies  during  rest  and  work,  partly  while  fasting 
and  partly  on  a  mixed  diet.  The  experiments  were  made  on  a 
full-grown  man  weighing  70  kilos.  The  results  are  contained  in 
the  following  table: 

TABLE  XIII. 

Consumption  of 

, ' ,  Water 

Proteids.  Fat.  Carbohydrates.  COj  eliminated.  O  consumed,  expired, 

Tj,    ,.  (Rest..    78       215  ...  716  761  889 

i-asting...  ^  ^^j.jj.    ^5       ggQ  __  1187  1073  1777 

-M-     J  ..  ^  (Rest..  137         65  353  913  831  828 

Mixed  diet  ^  ^p^j^  13^       173  353  1309  980  1413 

The  work  in  this  case  had  no  influence  on  the  destruction  of 
proteids,  while  the  consumption  of  non-nitrogenized  bodies  and 
the  elimination  of  water  by  the  skin  and  lungs  was  considerably 
increased. 

The  question  of  the  exchange  of  material  in  sleep  and  waking 
stands  in  close  relationship  to  the  exchange  of  material  in  rest  and 
activity.  According  to  PETTEiiTKOFER  and  Voit,  the  metabolism  of 
proteids  is  not  constantly  influenced  by  these  two  different  condi- 
tions; on  the  other  hand,  the  production  of  carbon  dioxide  is 
habitually  greater  during  the  day  than  in  the  night.     If  excessive 


EXCHANGE  OF  MATERIAL.  469 

work  has  been  done  during  the  day,  the  elimination  of  carbon 
dioxide  may  be  decreased  during  the  following  night.  In  sleep 
tlie  metabolism  of  non-nitrogenized  substance  is  indeed  smaller 
than  in  rest  without  sleep  (Levin),  and  it  is  less  the  more  sound 
the  sleep. 

The  reason  for  the  less  abundant  elimination  of  carbon  dioxide 
in  sleep  does  not  only  depend  upon  muscular  rest  but  also  on 
several  other  conditions,  among  which  are  the  absence  of  light  and 
other  excitants  which  act  in  the  day  and  which,  as  it  seems,  cause 
a  reflex  of  the  chemical  tonus  of  the  muscles  and  thereby  produce 
an  exchange  of  material.  Such  a  regulation  of  the  exchange  of 
material  and  the  production  of  heat  brought  about  by  the  nerves 
of  the  skin  which  is  produced  by  the  influence  of  the  chemical 
tonus  of  the  muscles  shows  that  the  external  temperature  is  of  the 
greatest  importance  in  the  exchange  of  material. 

Action  of  the  temperature  of  the  surrounding  air.  In  cold- 
blooded animals  the  production  of  carbon  dioxide  increases  and 
decreases  with  the  rise  and  fall  of  the  surrounding  temperature. 
In  warm-blooded  animals  this  condition  is  the  reverse.  By  the 
investigations  of  Ludwig  and  Sandeks-Ezx,  Pflugee,  Duke 
Charles  Theodore  of  Bavaria,  and  others,  it  has  been  demon- 
strated that  in  warm-blooded  animals  the  change  in  the  external 
temperature  has  different  results,  according  as  the  animal's  own 
heat  remains  the  same  or  changes.  If  the  temperature  of  the 
animal  sinks,  the  elimination  of  carbon  dioxide  also  sinks;  if  the 
temperature  rises,  the  elimination  of  CO,  also  rises.  If,  on  the 
contrary,  the  temperature  of  the  body  remains  unchanged,  then  the 
elimination  of  carbon  dioxide  increases  with  a  lower  and  decreases 
with  a  higher  external  temperature.  This  condition  may  be  ex- 
plained, according  to  Pfluger  and  Zuntz,  by  the  statement  that 
the  low  temperature,  by  exciting  a  reflex  action  in  the  sensitive 
nerves  of  the  skin,  causes  an  increased  metabolism  of  the  muscles 
with  an  increased  production  of  heat  affecting  the  temperature  of 
the  body.  The  increased  exchange  of  material  produced  at  a  low 
external  temperature  only  applies,  as  far  as  is  known,  to  the  non- 
nitrogenized  substances,  but  not  to  the  proteids. 

Weight  of  Body  and  Age.  The  greater  the  mass  of  the  body  the 
greater  the  absolute  consumption  of  material ;  while,  other  things 


470  PHYSIOLOGICAL   CHEMISTRY. 

being  equal,  ou  the  contrary,  as  above  stated  in  speaking  of  the 
exchange  of  material  in  starvation,  a  small  individual  of  the  same 
species  of  animal,  because  of  its  relatively  greater  surface  of  body 
and  therefore  its  relatively  greater  surface  of  heat,  decomposes 
relatively  more  substance.  With  about  the  same  bodily  weight 
the  destruction  of  proteids  is  smaller  with  a  greater  amount  of  fat. 
In  women,  who  generally  have  less  bodily  weight  and  greater 
amount  of  fat  than  men,  the  consumption  of  proteids  and  the 
metabolism  of  material  in  general  is  therefore  smaller,  and  the 
latter  is  ordinarily  about  f  of  that  of  men.  Otherwise  the  sex  does 
not  seem  to  hrve  any  special  influence  on  the  exchange  of  material. 

Young  animals  have,  for  the  reason  above  mentioned  (page  444), 
a  greater  exchange  of  material  than  older  ones,  and  they  decompose 
a  greater  quantity  of  substance  per  kilo.  In  regard  to  the  exchange 
of  material  in  children  the  investigations  of  Scharling  and  EoR- 
STER  on  the  elimination  of  carbon  dioxide,  and  of  Camerer  on  the 
elimination  of  urea,  are  important. 

FoRSTER  found  in  children  at  the  ages  given  and  at  rest  the 
following  elimination  of  carbon  dioxide  per  kilo  in  one  hour: 

3-5  vears ■ 1.17  grms.  COa 

e-T"  "     I.IT    " 

9-13  "     0.90     " 

In  a  grown  man  at  rest  Pettenkofer  and  VoiT  found  the 
elimination  of  carbon  dioxide  with  a  mixed  diet  was  0.55  grm.  per 
kilo  in  one  hour.  In  children  of  3  to  7  years  the  elimination  of 
CO2  per  kilo  is  more  than  double  that  of  grown  persons.  At  the 
age  of  16  years  the  elimination  of  carbon  dioxide  per  kilo  is  about 
the  same  as  in  grown  persons. 

Camerer  has  found  the  following  results  as  to  the  elimination 
of  urea  in  children : 

TABLE  XIV. 

As;e.  Weight  of  Body  in  Eilos.  Urea  in  grms. 

Per  Day.  Per  Kilo. 

7  months 6.50  5.0  0.75 

li  years 8.95  18.1  1.35 

3  '     12.61  11.1  0.90 

4  "  17.43  14.6  0.84 

5  "  16.20  12.3  0.76 

7  "  18  80  13.9  0.74 

9  "  25.10  17.3  0.69 

12.^     "     32.60  17.6  0.54 

15'     "     35.70  17.9  0.50 


EXCHANGE  OF  MATERIAL.  471 

In  adults  weighing  about  70  kilos  about  30  to  35  grms.  urea  per 
day  are  eliminated,  or  0.5  grni.  per  kilo.  At  about  15  years  of  age 
the  destruction  of  proteids  per  kilo  is  about  the  same  as  in  adults. 
The  relatively  greater  metabolism  of  proteids  in  young  individuals 
is  explained  partly  by  the  fact  that  the  metabolism  of  material  in 
general  is  more  active  in  young  animals,  and  partly  by  the  fact  that 
the  young  animal  is  as  a  rule  poorer  in  fat  than  the  grown  ones. 

V.     Potential  Energy  and  the  Relative  Nutritive  Value  of 
Various  Organic  Foods. 

With  the  organic  foods  the  organism  receives  a  supply  of  poten 
tial  energy  which  is  converted  into  living  force  in  the  body.  This 
potential  energy  of  the  various  foods  may  be  represented  by  the 
amount  of  heat  which  is  set  free  in  their  combustion.  This  quan- 
tity of  heat,  expressed  in  calories,  if  we  consider  the  calorie  as  that 
quantity  of  heat  which  is  necessary  to  raise  1  grm.  of  water  from 
0°  C.  to  1°  C,  is  the  following  for  1  grm.  of  the  substance. 

TABLE  XV. 

Calories  iu  Calories  in 

Dry  Substance.    Ash-free  Substance. 

Proteids  (in  meat) 5754  5778  1 

Muscle    5o45  5656  \  Rubner. 

Fat  (pig-fat,  melt.  pt.  +  43°) 9433  \ 

Grape-sugar 3693 1 

Milk-sugar 3877  !  ^^  „„   „ 

Cane-su|ar 3959     bTOHMANN. 

Starch 4116  J 

Fat  and  carbohydrates  are  completely  burnt  in  the  body,  and  we 
can  therefore  consider  their  combustion  equivalent  as  a  measure  of 
the  living  force  developed  by  them  within  the  organism.  The  pro- 
teids act  differently.  They  are  only  incomj^letely  burnt,  and  they 
yield  certain  products  of  decomposition  which,  leaving  the  body 
with  the  excreta,  still  represent  a  certain  amount  of  potential 
energy  which  is  lost  for  the  body.  The  heat  of  combustion  of  the 
proteids  is  smaller  within  the  organism  than  outside  of  it,  and  they 
must  therefore  be  specially  determined.  For  this  purpose  Eubner 
fed  a  dog  on  washed  meat.     He  subtracted  from  the  heat  of  com- 


472  PHYSIOLOGICAL   CHEMISTRY. 

bustion  of  the  food  the  heat  of  combustion  of  the.uiine  and  faeces, 
which  corresponded  to  the  food  taken  plus  the  quantity  of  heat 
necessary  for  the  swelling  up  of  the  albuminous  bodies  and  the 
solution  of  the  urea.  EuBiirER  has  also  tried  to  determine  the  heat 
of  combustion  of  the  proteids  (muscle-proteids)  decomposed  in  the 
body  of  rabbits  in  starvation.  According  to  these  investigations, 
the  physiological  heat  of  combustion  in  calories  for  each  gramme  of 
substance  is  as  follows : 

TABLE  XTI. 

1  grm.  of  the  Dry  Substance.  Calories. 

Proteids  from  meat 4424 

Muscle 4000 

Proteids  la  starvation 3843 

Fat  (average  for  various  fats) 9300 

Carbohydrates  (calculated  average) 4100 

The  physiological  combustion  value  of  the  various  foods  belong- 
ing to  the  same  group  is  not  quite  the  same.  It  is,  for  instance, 
3969  calories  for  a  vegetable  albuminous  body,  conglutin,  and  4434 
calories  for  an  animal  albuminous  body,  syntonin.  According  to 
EuBNER,  we  may  consider  the  normal  heat  value  per  1  grm.  of  ani- 
mal proteid  as  4233  calories,  and  of  vegetable  proteid  as  3960  calo- 
ries. When  a  person  on  mixed  diet  takes  about  60^  of  the  proteids 
from  animal  foods  and  about  40^  from  vegetable  foods,  then  we 
may  consider  as  the  value  of  1  grm.  of  the  proteid  of  the  food  as 
about  4100  calories.  The  physiological  value  for  each  of  the  three 
chief  groups  of  organic  foods,  by  their  decomposition  in  the  body, 
is  in  round  numbers  as  follows : 

TABLE  XVII. 

Calories. 

1  grm.  proteid =  4100 

1     "     fat =9300 

1     "     carbohydrate =  4100 

As  above  stated  several  times,  the  fats  and  carbohydrates  may 
decrease  the  metabolism  of  proteids  in  the  body,  while,  on  the  other 
hand,  the  quantity  of  proteids  in  the  body  or  in  the  food  acts  on 
the  metabolism  of  fat  in  the  body.  In  the  physiological  combustion 
the  various  foods  may  replace  one  another  to  a  certain  extent,  and 
it  is  therefore  important  to  know  in  what  proportion  they  replace 
one  another.     The  investigations  made  by  Kubner  have  taught  us 


FOOD  NEEDED  BT  MAN  UNDER   VARIOUS  CONDITIONS.  473 

that  when  we  wish  to  diminish  the  loss  of  fat  or  to  accumulate  fat 
it  takes  place  in  proportions  that  correspond  to  the  figures  of  the 
heat  value  of  the  same.  This  is  apparent  from  the  following  table. 
In  this  we  find  the  weight  of  the  various  foods  equal  to  100  grms. 
fat,  a  part  determined  from  experiments  on  animals  and  a  part 
calculated  from  figures  of  the  heat  values. 

TABLE  XVIII. 

100  grms.  fat  are  equal,  to  or  isodynamic  with : 

From  Experiments  From  the  Difference, 

on  animals.  Heat  Value.  per  cent. 

Syntonin 225  213                      +5.6 

Muscle-Hesh  (dried) ..  243  235                      -4-4.3 

Starch 232  229                      +1.3 

Cane-sugar 234  335                       —  Q 

Grape-sugar 256  253                       —  0 

From  the  given  isodynamic  value  of  the  various  foods,  it  follows 
that  these  substances  replace  one  another  in  the  body  almost  in 
exact  ratio  to  the  potential  energy  contained  in  them.  Thus  in 
round  numbers  240  grms.  carbohydrate  are  equal  to  or  isody- 
namic with  100  grms.  fat,  but  only  in  regard  to  its  ability  to  pre- 
vent the  loss  of  fat.  In  regard  to  the  sparing  of  proteids  the 
carbohydrates  accomplish  more  than  the  same  quantity  of  fat 
(page  463).  The  knowledge  of  these  isodynamic  values,  as  well  as  of 
the  potential  energy  in  the  various  foods,  is  of  fundamental  impor- 
tance in  the  calculation  of  the  diet  of  human  beings  under  various 
conditions. 

VI.  The  Need  of  Man  for  Food  under  Various  Conditions. 

Various  attempts  have  been  made  to  determine  the  daily  amount 
of  organic  food  needed  by  man.  Certain  investigators,  such  as 
Platfaik,  Moleschott,  and  others,  have,  from  the  total  consump- 
tion of  food  by  a  large  number  of  similarly-fed  individuals,  soldiers, 
sailors,  laborers,  etc.,  calculated  the  average  quantity  of  food 
required  per  head.  Others,  such  as  Pakkp:s,  Smith,  and  Voit, 
have  calculated  the  daily  demand  of  food  from  the  quantity  of 
carbon  and  nitrogen  in  the  excreta.  Others  again,  as  Petten- 
KOFER  and  Voit,  have  calculated  the  quantity  of  nutritive  material 
in  a  diet  by  which  an  equilibrium  was  maintained  in  the  individual 
for  one  or  several  days  between  the  consumption  and  elimination 
of  carbon  and  nitrogen.     Lastly,  others,  especially  Foester,  have 


474 


PHYSIOLOGICAL  CHEMISTRY. 


quantitatively  determined  during  a  period  of  several  days  the 
organic  nutritive  substances  consumed  daily  by  persons  choosing 
their  own  food,  who  were  employed  in  various  industries,  and  on 
which  they  felt  well  and  fully  capable  of  labor. 

Among  these  methods  a  few  are  not  quite  free  from  reproach 
and  others  have  not  as  yet  been  tried  on  a  sufficiently  large  scale. 
Nevertheless  the  experiments  collected  thus  far  serve,  partly  be- 
cause of  their  number  and  partly  because  of  the  methods,  to  correct 
and  control  one  another,  and  also  serve  as  a  good  starting-point  in 
determining  the  diet  of  various  classes  and  similar  questions. 

If  we  convert  the  quantity  of  nutritive  substance  daily  taken 
into  calories,  produced  during  physiological  combustion,  we  then 
obtain  some  idea  of  the  sum  of  the  chemical  tension  which  under 
different  conditions  is  introduced  into  the  body.  It  must  not  be 
forgotten  that  the  food  is  never  completely  absorbed  and  that 
undigested  or  unabsorbed  residues  are  always  expelled  from  the 
body  with  the  fseces.  The  gross  results  of  calories  calculated  from 
the  food  taken  must  therefore,  according  to  Rubner,  be  dimin- 
ished at  least  8^. 

The  following  summary  contains  certain  examples  of  the 
quantity  of  food  which  is  consumed  by  individuals  of  various 
classes  under  different  conditions.  In  the  last  column  we  also  find 
the  amount  of  living  force,  calculated  as  calories,  which  corresponds 
to  the  quantity  of  food  in  question  with  the  above-stated  correction. 
The  calories  are  therefore  net  results,  while  the  figures  for  the 
nutritive  bodies  are  gross  results. 

TABLE    XIX. 

Proteids.  Fat,  Carbohydrates.  Calories.  Authority. 

Soldier  during  peace. ..  119  40  629  3784  Playfair. 

light  service .. .  117  35  447  2434  Hildesheim. 

"      infield 146  44  504  2852 

Laborer 130  40  550  2903  Moleschott. 

"        at  rest 137  72  352  2458  Pettenkofer  &  VoiT. 

Cabinet-maker  (40  years)  131  68  494  28:55  Fokster. 

Young  physician 127  89  362  2602 

134  102  292  2476 

Laborer 133  95  422  2902 

English  smith 176  71  666  3780  Playfair 

pugilist 288  88  93  2189 

Bavarian  wood-chopper  135  208  876  5589  Liebig. 

Laborer  in  Silesia 80  16  552  2518  Meinert. 

Seamstress  in  London..     54  29  292  1688  Playfair. 


FOOD  NEEDED  BY  MAN   UNDER   VARIOUS  CONDITIONS.    475 

It  is  evident  that  persons  of  essentially  different  weight  of  body 
who  live  under  unequal  external  conditions  must  need  essentially 
different  food.  It  is  also  to  be  expected  (and  this  is  confirmed  by 
the  table)  that  not  only  the  absolute  quantity  of  food  consumed  by 
various  persons,  but  also  the  relative  projDortion  of  the  various 
organic  nutritive  substances,  shows  considerable  variation.  Eesults 
for  the  daily  need  of  human  beings  in  general  cannot  be  given.  For 
certain  classes  of  human  beings,  such  as  soldiers,  laborers,  etc., 
results  may  be  given  which  are  valuable  for  the  calculation  of  the 
daily  rations. 

Based  on  extensive  investigations  and  a  veiy  wide  experience, 
VoiT  has  proposed  the  following  average  quantities  for  the  daily 
diet  of  adults  : 

Proteids.  Fat.  Carbohydrates.         Calories. 

For  men. . . .  118  grms.  56  grms.  500  grms.  2810 

But  we  must  here  remark  that  these  statements  relate  to  a  man 
weighing  70  to  75  kilos  and  who  was  engaged  daily  for  ten  hours 
with  not  too  fatiguing  labor. 

The  amount  of  food  required  by  a  woman  engaged  in  moderate 
labor  is  about  ^  that  of  a  laboring  man,  and  we  may  consider  the 
'oil owing  as  a  daily  diet  with  moderate  work. 

Proteids.  Fat.  Carbohydrates.       Calories. 

For  women . .   94  grms.  45  grms.  400  grms.  2240 

The  proportion  of  fat  to  carbohydrates  is  here  as  1 : 8-9.  Such 
a  proportion  occurs  often  in  the  food  of  the  poorer  classes,  while  the 
ratio  in  the  food  of  wealthier  persons  is  1:  3-4.  The  maximum 
quantity  of  carbohydrates  in  the  food  must,  according  to  Voit,  be 
above  500  grms.  ;  and  as  the  carbohydrates  besides  constitute  the 
chief  part  of  the  often  very  bulky  vegetable  foods,  it  has  been  sug- 
gested and  is  desirable  on  this  and  other  grounds  to  increase  the 
quantity  of  fat  at  the  expense  of  the  carbohydrates  in  such  rations. 
But  because  of  the  high  price  of  fat  such  a  modification  cannot 
always  be  made. 

In  judging  the  above  numbers  for  the  daily  rations  it  must  not 
be  forgotten  that  the  figures  for  the  various  nutritive  bodies  are 
gross  results.       They  consequently  represent  the  quantity  of   the 


476  PHTSIOLOOICAL   CHEMISTRY. 

nutritive  jodies  which  must  be  taken  in,  and  not  those  which  are 
really  absorbed.  The  figures  for  the  calories,  which  here  and  in  the 
following  pages  are  so-called  gross  calories  are,  on  the  contrary,  net 
results. 

The  various  foods  are,  as  is  well  known,  not  equally  digested 
and  absorbed,  and  in  general  the  vegetable  foods  are  less  completely 
used  up  than  animal  foods.  This  is  especially  true  of  the  proteids. 
When,  therefore,  VoiT,  as  above  stated,  calculated  the  daily  amount 
of  proteids  needed  by  a  laborer  as  118  grms.,  he  starts  with  the 
supposition  that  the  diet  is  a  mixed  animal  and  vegetable  one,  and 
also  that  of  the  above  118  grms.  about  105  grms.  are  absorbed. 
The  results  obtained  by  Pfluger  and  his  school,  Bleibtreu  and 
BoHLAND,  for  the  extent  of  the  metabolism  of  proteids  in  man  with 
a  diet  optional  and  sufficient  correspond  well  with  the  above  figures 
— when  the  unequal  weight  of  the  body  of  the  various  persons 
experimented  upon  is  sufficiently  considered. 

As  a  rule,  as  a  more  exclusively  vegetable  food  is  employed,  the 
amount  of  proteids  in  the  same  is  also  habitually  smaller.  The 
strictly  vegetable  diet  of  certain  people — as  of  the  Japanese — and 
that  of  the  so-called  vegetarians  is  therefore  a  proof  that  a  person, 
if  the  quantity  of  food  be  sufficient,  may  exist  on  considerably 
smaller  quantities  of  proteids  than  VoiT  suggests.  It  follows  from 
the  investigations  of  Hirschpeld  and  Kumagawa  that  a  nearly 
complete  or  indeed  a  complete  nitrogenous  equilibrium  may  be 
attained  by  the  sufficient  administration  of  non-nitrogenized  nutri- 
tive bodies  with  relatively  very  small  amounts  of  proteids.  Hirsch- 
feld,  who  weighed  73  kilos,  could  maintain  nitrogenous  equilibrium 
very  nearly  with  a  diet  containing  43.5  grms.  nitrogenized  bodies, 
165  grms.  fat,  354  grms.  carbohydrates,  and  42.7  grms.  alcohol. 
Kumagawa  made  experiments  on  himself  with  a  purely  vegetable 
diet,  consisting  mainly  of  boiled  rice.  On  an  average  50.5  grms. 
proteids  and  569.83  grms.  carbohydrates  were  daily  introduced,  and 
of  this  37.82  grms.  proteids  and  566.7  grms.  were  daily  used  up 
By  this  food  he  was  not  able  with  a  bodily  weight  of  48  kilos  to 
attain  nitrogenous  equilibrium,  but  he  found  indeed  that  a  part  of 
the  nitrogen  was  retained  in  the  body.  The  weight  of  the  body 
increased  and  the  general  condition  was  good.  The  total  amount 
of  calories  in  the  absorbed  food  was  in  this  case  2500  in  round  num- 


FOOD  NEEDED  BY  MAN  UNDER   VARIOUS  CONDITIONS.    477 

bers.  or  52  per  kilo.  It  follows  from  the  experiments  just  men- 
tioued  that  an  adult  may  be  sufficiently  nourished  with  a  consider- 
ably smaller  quantity  of  proteids  than  Voit  considers  necessary,  if 
the  total  food  corresponds  to  the  demands  of  the  body  in  calories, 
which  may  be  accomplished  by  a  corresponding  increase  in  the  ad- 
ministration of  non-nitrogenized  nutritive  bodies. 

If  we  keep  in  mind  that  the  food  of  people  of  different  coun- 
tries varies  greatly,  and  that  the  individual  also  takes  essentially 
different  nourishment  according  to  the  external  conditions  of  liv- 
ing and  the  influence  of  climate,  it  is  not  remarkable  that  a  person 
accustomed  to  a  mixed  diet  cannot  exist  for  a  long  time  on  a  strictly 
vegetable  diet  deficient  in  proteids,  even  though  not  especially 
difficult  to  digest.  No  one  doubts  the  ability  of  man  to  adapt 
himself  to  a  heterogeneously-composed  diet  when  this  is  not  too  dif- 
ficult of  digestion  and  is  sufficient;  but  this  ability  does  not  seem 
sufficient  reason  for  essentially  altering  the  figures  suggested  by 
Voit.  Voit's  figures  are  based  on  comprehensive  experiments,  alsa 
on  experience  and  exact  knowledge  of  the  actual  existing  condi- 
tions, and  they  are,  which  is  especially  important,  as  above  stated, 
only  given  for  certain  cases  or  certain  classes  of  people.  It  is  not 
denied  by  any  one  that  these  results  are  not  applicable  to  all  cases, 
as  it  is  evident  that  the  daily  ratioii  necessary  for  a  laborer  given 
by  Voit  must  be  altered  somewhat  for  other  countries  because  of 
the  existing  conditions  in  middle  Europe,  where  Voit  made  his  in- 
vestigations. With  regard  to  the  conditions  in  Sweden  we  may 
propose  as  the  daily  diet  of  a  laboring  man  about  120  grms.  pro- 
teids, 100  grms.  fat,  and  400-450  grms.  carbohydrates.  These 
figures  are  based  on  the  experience  obtained  in  Sweden  and  cal- 
culations made  by  the  author. 

If  we  compare  the  figures  of  Table  XIX  with  the  average  figures 
proposed  by  Voit  for  the  daily  diet  of  a  laborer,  it  would  seem  at 
the  first  glance  as  if  the  consumed  food  in  certain  cases  was  con- 
siderably in  excess  of  the  need,  while  in  other  cases,  as  for  instance 
for  the  seamstress  in  London,  it  was  entirely  insufficient.  A  posi- 
tive conclusion  cannot,  therefore,  be  drawn  if  we  do  not  know  the 
weight  of  the  body  as  well  as  the  labor  performed  by  the  person, 
and  also  the  conditions  of  living.  It  is  certainly  true  that  the 
amount  of  nutriment  required  by  the  body  is  not  directly  propor- 


478  PHYSIOLOGICAL  CHEMISTRY. 

tional  to  the  bodily  weight,  for  a  small  body  consumes  relatively 
more  substance  than  a  larger  one,  and  varying  amounts  of  fat  may 
also  cause  a  difference;  but  a  large  body,  which  must  maintain  a 
greater  quantity,  consumes  an  absolutely  greater  quantity  of  sub- 
stance than  a  small  one,  and  in  estimating  the  nutritive  need  one 
must  also  always  consider  the  weight  of  the  body.  According  to 
VoiT,  the  diet  for  a  laborer  with  70  kilos  bodily  weight  requires  40 
calories  for  each  kilo.  In  Kumagawa's  series  of  experiments,  in 
which  the  absolute  quantity  of  food  was  smaller,  the  average  was 
52  calories  for  each  kilo. 

As  above  stated  several  times,  the  demands  of  the  body  for  nour- 
ishment vary  with  its  different  conditions.  Among  these  condi- 
tions two  are  practically  important,  namely,  labor  and  rest. 

In  a  previous  chapter,  in  which  muscular  labor  was  spoken  of,  it 
was  seen  that  the  generally  accepted  view  is  that  non-nitrogenized 
food  is  the  most  essential,  if  not  the  exclusive,  source  of  muscular 
force.  As  a  natural  sequence  it  is  to  be  expected  that  in  activity 
the  non-nitrogenized  foods  before  all  must  be  increased  in  the  daily 
rations. 

Still  this  does  not  seem  to  correspond  to  daily  experience.  It 
is  a  well-known  fact  that  hard-working  individuals — men  and  ani- 
mals— require  a  greater  amount  of  proteids  in  the  food  than  less 
active  ones.  This  contradiction  is,  however,  only  apparent,  and  it 
depends,  as  Voit  has  shown,  upon  the  fact  that  individuals  used 
to  violent  work  are  more  muscular.  For  this  reason  a  person  per- 
forming severe  muscular  labor  requires  food  containing  a  larger  pro- 
portion of  proteids  than  an  individual  whose  occupation  demands 
less  violent  exertion.  Another  question  is,  how  should  the  relative 
and  absolute  amount  of  food  be  changed  if  increased  exertion  be 
demanded  of  one  and  the  same  individual  ? 

An  answer  based  upon  experience  may  be  found  in  statistics 
concerning  the  maintenance  of  soldiers  in  peace  and  in  war.  Many 
such  statements  are  obtainable.  In  a  critical  examination  of  the 
same  it  was  found  that  in  war-rations  the  quantity  of  non-nitrogen- 
ized bodies  as  compared  to  the  proteids  is  only  increased  in  excep- 
tional cases,  while  usually  the  reverse  is  the  case.  Even  in  these 
oases  the  actual  proportion  does  not  correspond  to  the  theoretical 
demand  upon  which,  however,  too  great  stress  must  not  be  placed. 


FOOD  NEEDED  BY  MAN   UNDER   VARIOUS  CONDITIONS.    479 

since  in  the  case  of  soldiers  in  the  field  many  other  circumstances 
are  to  be  considered,  such  as  the  volume  and  weight  of  the  food, 
etc.,  etc.,  which  cannot  here  be  more  closely  discussed.  The  fol- 
lowing table  shows  the  average  results  of  soldiers'  rations  in  war 
and  peace,  calculated  by  Almen  from  the  detailed  statement  of 
several  countries.' 

These  average  results  also  include  the  figures  for  Sweden. 

TABLE   XX. 

A.    Peace  Ration.  B.    War  Ratiou. 

Proteids.  Fat.  Carb.  Proteids.    Fat.  Carb. 

Miuimum 108  22  504  126         38  484 

Maximum 165  97  7ol  197          95  688 

Meau 130  40  531  146         59  557 

Sweden  (proposed).   179  102  591  202        137  565 

If  we  do  not  consider  the  very  abundant  rations  proposed  for 
the  soldier  in  Sweden,  and  if  we  only  adhere  to  the  above  mean 
figures,  we  obtain  the  following  results  for  the  daily  rations: 

Proteids.        Fat.  Carb.         Calories. 

In  peace 130  40  531  2900 

luwar 146  59  557  3250 

If  we  calculate  the  fat  in  its  equivalent  amount  of  starch,  then 
the  relation  of  the  proteids  to  the  non-nitrogenized  foods  is  : 

In  peace 1 :  4.97 

In  war 1  :  4.79 

The  proportion  is  nearly  the  same  in  both  cases  ;  the  small  dif- 
ference which  occurs  shows  a  slight  relative  increase  in  the  proteids 
in  the  war  ration.  On  the  contrary,  what  is  especially  apparent 
from  the  total  of  the  calories,  the  total  quantity  of  nutritive  bodies 
is  greater  in  the  war  than  in  the  peace  ration. 

As  more  work  requires  an  increase  in  the  absolute  quantity  of 
food,  so  the  quantity  of  food  must  be  diminished  when  little  work 
is  performed.  The  question  as  to  how  far  this  can  be  done  is  of 
importance  in  regard  to  the  diet  in  prisons  and  poor-houses.  We 
give  below  the  following  as  example  of  such  diets. 

'  Germany,  Austria,  Switzerland,  France,  Italy,  Russia,  and  the  United  States. 


480  PHYSIOLOGICAL   CHEMISTRY. 


TABLE  XXI. 

Proteids.  Fat.  Carb.  Calories. 

Prisoner  (not  working). ...  87  22  305         1667       Schuster. 

....  85  30  300         1709       Voit. 

Man  in  poor-house 92  45  332         1985       Forster. 

Woman  in    "  80  49  266         1725 

The  figures  given  by  VoiT  are,  according  to  him,  the  lowest  fig- 
ures for  a  non-working  prisoner.  He  considers  the  following  as 
the  lowest  diet  for  old  non-working  people : 

Proteids.       Fat.  Carb.  Calories. 

Men 90  40  350  2200 

Women 80  35  300  1733 

In  calculating  the  daily  diet  it  is  in  most  cases  sufficient  to 
ascertain  how  much  of  the  various  nutritive  bodies  must  be  daily 
administered  to  the  body  to  keep  it  in  the  proper  condition  to  per- 
form the  work  required  of  it.  In  other  cases  it  may  be  required  to 
improve  the  nutritive  condition  of  the  body  by  properly  selected 
food  ;  but  we  also  have  cases  in  which  we  desire  to  diminish  the 
mass  or  weight  of  the  body  by  an  insufficient  nutrition.  This  is 
especially  the  case  in  obesity,  and  all  the  dietaries  proposed  for  this 
purpose  are  chiefly  starvation  cures. 

The  oldest  and  most  generally-known  diet  cure  for  corpulency 
is  that  of  Harvey,  which  is  ordinarily  called  the  Banting  method. 
The  principle  of  this  cure  consists  in  increasing,  as  far  as  possible, 
the  consumption  of  the  accumulated  fat  of  the  body  by  as  limited 
a  supply  of  fat  and  carbohydrates  as  possible  and  a  simultaneous 
increased  supply  of  proteids.  A  second  cure,  called  Ebstein's 
cure,  is  based  on  the  assumption  (not  correct)  that  the  fat  of  the 
food  is  not  accumulated  in  a  body  rich  in  fat,  but  is  completely 
burnt.  In  this  cure  large  quantities  of  fat  are  therefore  allowed  in 
the  food,  while  the  quantity  of  carbohydrates  is  diminished  very 
much.  The  third  cure,  called  Oertel's  cure,  is  based  on  the  cor- 
rect view  that  a  certain  quantity  of  carbohydrates  has  no  greater 
influence  in  the  accumulation  of  fat  than  the  isodynamic  quantities 
of  fat.  In  this  cure,  therefore,  carbohydrates  as  well  as  fat  are 
allowed,  provided  the  total  quantity  of  the  same  is  not  so  great  as 
to  hinder  the  decrease  in  the  fatty  condition.     A  greatly  dimin- 


FOOD  NEEDED  BY  MAN   UNDER   VAB^IOUS  CONDITIONS.   481 

ished  supply  of  water  is  also  one  of  the  features  of  Oertel's  cure, 
especially  in  certain  cases.  The  average  amount  of  the  various 
nutritive  substances  supplied  to  the  body  in  these  three  cures  is  as 
follows,  and  we  give  also  for  comparison  in  the  same  table  Voit's 
diet  necessary  for  a  laborer. 

TABLE  XXII. 

Proteids.  Fat.  Garb.  Calories. 

Harvey-Banting's  cure...  171  8  75           1066 

Ebstein's  cure 103  85  47            1391 

Oertel's      "    156  22  72            1124 

"   (max.) 170  44  114            1557 

Laborer,  according  to  Voit.  118  56  500            2810 

If  the  fat  in  all  cases  is  recalculated  in  starch,  then  the  pro- 
portion of  the  proteids  to  the  carbohydrates  is  : 

Harvey-Banting  cure 100  :    54 

Ebstein's  cure 100  :  246 

Oertel's      " 100  :    80 

"    (max.) 100:129 

Laborer 100  :  540 

In  all  these  cures  for  corpulence  the  quantity  of  non-nitrogen- 
ized  bodies  is  diminished  as  compared  to  the  proteids;  but  chiefly 
the  total  quantity  of  food,  as  is  shown  by  the  number  of  calories,  is 
considerably  diminished. 

Harvey-Banting's  cure  differs  from  the  others  in  a  relatively 
very  much  greater  amount  of  proteids,  while  the  total  number  of 
calories  in  it  is  the  smallest.  On  this  account  this  cure  acts  verj 
quickly;  but  it  is  therefore  also  more  dangerous  and  more  difficult 
to  accomplish.  In  this  regard  Ebstein's  and  Oertel's  cures  (espe- 
cially Oertel's),  having  a  greater  variation  in  the  selection  of  food, 
are  better.  As  the  adipose  tissue  has  a  proteid-sparing  action,  we 
have  to  consider  in  using  these  cures,  especially  Banting's,  that 
the  destruction  of  proteids  in  the  body  is  not  increased  with  the 
decrease  in  the  adipose  tissue,  and  one  must  therefoj-e  carefully 
watch  the  elimination  of  nitrogen  by  the  urine.  All  diet  cures  for 
obesity  are  moreover,  as  above  stated,  starvation  cures  ;  and  if  the 
daily  amount  of  food  required  by  an  adult  man,  represented  as  cal- 
ories, is  in  round  numbers  2500  calories  (according  t-o  the  average 


48e  PHYSIOLOGICAL   CEEMISTRT. 

figures  found  by  Foester  in  the  case  of  a  physician),  then  one 
immediately  sees  what  a  considerable  part  of  its  own  mass  the  body 
must  daily  give  up  in  the  above  cures.  This  reminds  us  of  the 
great  care  necessary  in  employing  these  cures ;  but  each  special 
case  should  be  conducted  with  regard  to  the  individuality,  the 
weight  of  the  body,  the  elimination  of  nitrogen  in  the  urine,  etc., 
etc.,  and  always  under  strong  control  and  only  by  physicians,  never 
by  a  layman.  A  closer  discussion  of  the  many  conditions  which 
must  be  considered  in  these  cases  does  not  enter  into  the  plan  and 
scope  of  this  work. 


ANIMAL  FOODS. 
TABLE  I.— FOODS.' 


483 


1.  Animal  Foods. 


1000  Parts  contain 


Relationship  of 


a.  Flesh  without  Bones 

Fat  beef' 

Beef  (average  fat  *) 

Beef^ 

Corned  beef  (average  fat). . . . . 

Veal 

Horse,  salted  and  smoked. . . , 

Smoked  ham 

Pork,  salted  and  smoked  * 

Flesh  from  hare 

"         "     chicken 

"        "     partridge 

"        "     wild  duck . 

b.  Flesh  with  Bones. 

Fat  beef 

Beef,  average  fat^ 

Beef,  slightly  corned , 

Beef,  thoroughly  corned 

Mutton,  very  fat 

"        average  fat , 

Pork,  fresh,  fat 

Pork,  corned,  fat 

Smoked  ham , 

c.  Fishes. 

River  eel,  fresh,  entire , 

Salmon,        "  "  

Anchovy,      "  "  

Flounder,      "  "  ....... 

River  perch,"  "  , 

Torsk,  "  "  , 


183 
196 
190 
218 
190 
318 
255 
100 
233 
195 
253 
246 


156 
167 
175 
190 
135 
160 
100 
120 
200 


89 
121 
128 
145 
100 


166 

98 

120 

115 

80 

65 

365 

660 

11 

93 

14 

31 


141 
83 
93 
100 
382 
160 
460 
540 
300 


220 

67 

39 

14 

2 

1 


11    640 

18    688 

is;  672 

117,  550 

13!  717 

1251  492 

100    280 

40    130 

12!  744 

11  701 
141  719 

12  711 


9 

15 

85 
100 


544 

585 

480 

430 

437 

10   520 

5    365 

60'  200 

70'  340 


150 

150 

167 

180 

88 

150 

70 

80 

90 


352  333 

469  333 

489  333 

580  250 

440  450 

455  450 


100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 


100 
100 
100 
100 
100 
100 
100 
100 
100 


100 
100 
100 
100 
100 
100 


90 

50 

63 

53 

42 

20 

143 

660 

5 

48 

6 

13 


90 

49 

58 

53 

246 

100 

460 

450 

150 


246 

56 

31 

9 

2 
1 


»  The  results  in  the  following  tables  are  chiefly  compiled  from  the  summary  of  AmfiN 
and  of  KoNiG.  As  "  waste"  we  here  designate  that  part  of  the  foods  which  is  lost  in  the 
preparation  of  the  food  or  that  which  is  not  used  by  the  body;  for  instance,  the  bones, 
skin,  egg-shell,  and  the  cellulose  in  the  vegetable  foods. 

'  Meat  such  as  is  ordinarily  sold  in  the  markets  in  Sweden. 

•  Beef  such  as  is  delivered  by  large  purveyors  to  public  institutions  in  Sweden. 

*  Pork,  chiefly  from  the  breast  and  belly,  such  as  occurs  in  the  rations  of  Swedisb 
soldiers. 


484 


PHYSIOLOGICAL   CHEMI8TBT. 
TABLE  I.— FOOiy^.— (Continued.) 


Animal  Foods. 


Pike,  fresh,  entire 

Herring,  salted,  entire 

Anchovy,     "  "    

Salmon  (side),  salted 

Kabeljau  (salted  haddock) 

Codfish  (dried  ling) 

"      (dried  torsk) 

Fish-meal  from  variety  of  Gadus 

d.  Inner  Organs  (Fresh). 

Brain 

Beef -liver 

Beef-heart 

Heart  and  lungs  of  mutton 

Veal-kidney 

Ox-tongue  (fresh) 

Blood    from     various    animals 
(average  results) 

e.  Other  Animal  Foods. 

Kind    of    pork-sausage    (Mett- 

vpurst) 

Same  for  frying 

Butter 

Lard 

Meat  extract 

Cow's  milk  (full) 

"         "    (skimmed) 

Buttermilk 

Cream 

Cheese  (fat) 

"       (poor) 

Whey  cheese  (poor) 

Hen's  egg,  entire 

"        "     without  shell 

Yolk  of  egg 

White"    " 


1000  Parts  contain 


Pl(H 


82 
140 
116 
200 
246 
532 
665 
736 


116 
196 
184 
163 
221 
150 

182 


190 

220 

7 

3 

304 

35 

35 

41 

37 

230 

334 

89 

106 

123 

160 

103 


1 

140 

43 

108 

4 

5 

10 

7 


103 
56 
92 

106 
38 

170 


150 
160 
850 
990 

85 

7 

9 

257 

270 

66 

70 

93 

107 

307 

7 


11 


50 

50 

38 

35 

40 

50 

456 

4 

5 


6 

100 
107 
132 
178 
106 
59 
87 


50 
55 
15 

175 

7 

7 

7 

6 

60 

50 

56 

8 

10 

13 


461 
280 
334 
460 
472 
257 
116 
170 


770 
720 
714 
721 
728 
670 

807 


610 
565 
119 
7 
217 
873 
901 
905 
665 
400 
500 
329 
654 
756 
520 
875 


450 
340 
400 
100 
100 
100 
150 


135 


Relationship  of 


100 
100 
100 
100 
100 
100 
100 
100 


100 
100 
100 
100 
100 
100 

100 


100 
100 
100 
100 

100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 


1 

100 

37 
54 

1 
1 
1 
1 


28 
50 
65 
17 
113 


79 
73 
12100 
330U0 

100 
20 
22 

695 

117 
19 
79 
88 
88 

192 
7 


0 

0 

100 

0 

143 

143 

93 

95 

17 

15 

512 

4 

4 

0 

7 


VEGETABLE  FOODS 
TABLE  I.— FOOD'^.— {Continued.) 


485 


2.  Vegetable  Foods. 


Wheat  (grains) 

Wheat-flour  (fine) 

"         (very  tine) 

Wheat-bran 

Wheat-bread  (fresh) 

Macaroni 

Rye  (grains) 

Rye-flour 

Rye-bread  (dry) 

"       "      (fresh,  coarse) 

"      (fresh,  flue) 

Barley  (grains) 

Scotch  barley 

Oat  (grains) 

Oat  (peeled) 

Corn 

Rice  (peeled  for  boiling) 

French  beans 

Peas  (yellow  or  green) 

Flour  from  peas 

Potatoes 

Turnips 

Carrot  (yellow) 

Cauliflower 

Cabbage 

Beans 

Spinach 

Lettuce 

Cucumbers 

Radishes 

Edible  mushrooms  (average).. . 
Same  dried  in  the  air  (average) 

Apples  and  pears 

Various  berries 

Almonds 

Cocoa 


1000  Parts  contain 


3  " 


123 

110 

92 
150 

88 

90 
115 
115 
114 

77 

80 
111 
110 
117 
140 
101 

70 
232 
220 
270 

20 

14 

10 

25 

19 

27 

31 

14 

10 

12 

32 

219 

4 

5 

242 

1401  480 


537 


676 

740 

768 

489 

550 

768 

688 

720 

725 

480 

514 

654 

720 

563 

660 

656 

770 

537 

530 

520 

200 

74 

90 

50 

49 

66 

33 

22 

23 

38 

60 

412 

130 

90 

72 

180 


140 
120 
120 
130 
330 
131 
140 
110 
110 
400 
370 
140 
146 
130 
100 
140 
146 
137 
150 
125 
760 
893 
873 
904 
900 
888 
908 
944 
956 
934 
877 
160 
832 
849 
54 
55 


26 

2 

6 

192 

5 

22 
20 
16 
17 
11 
48 

100 
20 
28 
5 
37 
60 
45 
8 

10 

15 

9 

18 

12 

8 

7 

6 

8 

18 

123 

31 

50 

66 

95 


Relationship  of 


1  :2         :3 


100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 


14 

11 

12 
26 

11 

3 

15 

13 

18 

14 

18 

19 

9 

51 

43 

57 

10 

9 

7 

6 

10 
14 
20 
16 
11 
4 
16 
21 
10 
8 
12 
12 


222 
343 


549 
654 
835 
292 
625 
853 
600 
626 
634 
623 
634 
589 
654 
481 
471 
662 

1100 
231 
240 
192 

1030 
529 
900 
200 
258 
244 
106 
157 
230 
317 
188 
188 

3250 

1800 

30 

129 


486 


PHYSIOLOGICAL   CHEMISTRY. 
TABLE  II.— MALT  LIQUORS. 


1000  Parts  by  Weight 
contain 


Porter 

Beer  (Swedish) 

"     (Swedish  export). . . 

Draught-beer 

Lager-beer 

Bock-beer 

Weiss-beer 

Swedish  "  Svagdricka". . 


871 

887 
885 
911 
903 
881 
916 

945 


d  o 

«5 


76 


15 
7 
8 
4 
6 
5 


13 


65 
73 


10 

7 

18 


23  — 


<s 

a 

TS 

u 

O 

< 

>% 

O 

8 

— 

2 

3 

1.5 

2 

1.7 

— 

4 

— 

— 

— 

—       4 

5 
3 
2 
2 
3 


TABLE  III.-WINE  AND   OTHER  ALCOHOLIC  LIQUORS. 


1000  Parts  by  Weight 
contain 


,a 

P5  O  s 

6 

k< 

O  o 

c; 

h 

'a<DB 

a 

■§ 

^ 

o  3 

<^ 
o 

> 

g 
1 

1= 

02 

<1 

Si 

o 
>> 

5 

J3 

883 

94 

23 

6 

5.9 

2.0 

863 

115 

23 

4 

5.0 

2.0 

776 

90 

134 

115 

6.0 

1.0 

1.0 

801 

94 

105 

87 

6.0 

10 

2.0 

808 

120 

72 

51 

7.0 

9.0 

3.0 

795 

170 

35 

15 

5.0 

6.0 

5.0 

774 

164 

62 

40 

4.0 

2.0 

3.0 

791 

156 

53 

33 

5.0 

3.0 

3.0 

790 

164 

46 

35 

5.0 

4.0 

4.0 

479 

263 

460 

550 

442-590 

332 
260-475 

.2  " 

■?o 
5> 
D 


Bordeaux  wine. . . , 
White  wine  (Rheingau;. 

Champagne 

Rhine  wine  (sparkling). 

Tokay 

Sherry 

Port- wine 

Madeira 

Marsala 

Swedish  punch. . . 

Brandy 

French  cognac. . . 
Liqueurs , 


60-7a 


INDEX. 


Absorption,  227-232  ;  importauce  of  the 
cells  for  the  same,  225,  231,  232  ;  ac- 
tion on  the  putrefactive  processes  in 
ihe  intestines,  220. 

Absorption-ratio,  81 ;  of  the  blood-color- 
ing matters,  82. 

Acetic  acid,  in  the  gastric  juice,  177  ;  in 
the  contents  of  the  stomach,  196  ;  pas- 
sage into  the  urine,  374,  389. 

Aceto-acetic  acid,  422  ;  in  urine,  420, 
421. 

Acetone,  421  ;  in  blood,  114  ;  in  urine, 
420. 

Acetonuria,  421. 

Acetylen  hasmoglobin,  74. 

Acholia,  pigmentary,  158. 

Achroo-dextrin,  171, 

Acid  albuminate,  14  ;  properties  and  be- 
havior, 23,  24  ;  in  pepsin  digestion, 
182,  183. 

Acid  amides,  behavior  in  the  body,  389. 

Acid  rigor,  262. 

Acids,  organic,  behavior  in  the  body, 
389. 

Acidity,  of  the  contents  of  the  stomach, 
195  :  of  the  urine,  334. 

Acrolein,  244  ;  test,  244,  246. 

Actinochrom,  325. 

Acrylic  acid,  action  on  the  elimination 
of  uric  acid,  351. 


Acrylic  acid  di-ureid,  350. 

Adamkiewicz's  reaction,  20. 

Adenin,  48 ;  properties  and  occurrence, 
51 ;  in  urine,  359. 

Adhesion,  importance  in  the  coagula- 
tion of  blood,  89. 

Adipocere,  248. 

^gagropila,  226. 

Albumin  glands,  167. 

Albumins,  14 ;  general  properties,  20 
(see  also  various  albumins). 

Albumin,  detection  in  the  urine,  397 ; 
quantitative  estimation,  399  (see  also 
Protein  bodies). 

Albuminous  bodies,  general  behavior, 
reactions,  splitting  products  and  com- 
position, 15-21  ;  summary,  14,  22-30 
(see  also  various  albuminous  bodies  of 
the  tissues  and  fluids). 

Albuminate,  14  ;  properties  and  behav- 
ior, 23,  24  ;  ferruginous  albuminate  in 
the  spleen,  130. 

Albuminoids,  14,  34  ;  in  cartilage,  234, 
236  ;  in  the  yolk  membrane,  291. 

Albumoses,  14  ;  general  properties,  25- 
30  ;  in  the  putrefaction  of  proteids, 
216  ;  in  pepsin  digestion,  182  ;  in  tryp. 
sin  digestion,  206  ;  in  urine,  398  ;  nu- 
tritive value,  460. 

Alcapton,  365. 

487 


488 


INDEX. 


Alcohol,  see  Ethyl-alcohol. 

Alcoholic  fermentation,  7,  307,  409. 

Alanin,  39. 

Aleurone  crystals,  293. 

Alizarin,  in  the  urine,  393. 

Alizarin  blue,  behavior  in  the  tissues,  5. 

Alkali  albuminate,  14 ;  properties,  23, 
24  ;  in  the  eye,  280,  283  ;  in  the  yolk  of 
the  egg,  293  ;  in  the  brain,  273  ;  in  the 
non-striated  muscles,  272 ;  Lieber- 
kuhn's  alkali  albuminate,  23. 

Alkali  carbonate,  physiological  impor- 
tance, 452  ;  action  on  the  secretion  of 
gastric  juice,  176  ;  occurrence,  see  the 
various  tissues  and  fluids. 

Alkali  earths,  in  the  urine,  384  ;  in  the 
bones,  238,  239 ;  insufficient  supply, 
241. 

Alkali  phosphates,  in  urine.  384  ;  occur- 
rence, see  the  various  tissues. 

Alkali  urates,  in  sediments,  428  ;  in  cal- 
culi, 431. 

Alkaline  fermentation  of  the  urine,  374, 
427. 

Alkaloids,  action  on  the  muscles,  263  ; 
passage  into  the  urine,  393. 

Allantoic  fluid,  358. 

Allantoin,  properties,  occurrence,  etc., 
358  ;  formation  from  uric  acid,  350  ; 
in  transudations,  122,  124. 

Alloxan,  350. 

AiiMBN-BoTTGEK's  bismuth  test,  409, 
411. 

Almen's  guaiacum  test  for  blood,  402. 

Amanitin,  44. 

Ambergris,  227. 

Am  brain,  227. 

Amido-acids,  relation  to  the  formation 
of  urea,  338  ;  to  the  formation  of  uric 
acid,  352;  production  in  putrefaction, 
216 ;  in  pepsin  digestion,  182  ;  from 
protein  bodies,  15,  16.  35,  36,  206, 
216  ;  in  trypsin  digestion,  206. 

Amido-acetic  acid,  see  GlycocoU. 

Amido-acrolein,  37. 


Amido-caproic  acid,  see  Leucin. 

Amido-ciunamic  acid,  behavior  in  the 
organism,  391. 

Amido-ethylsulphuric  acid,  see  Taurin. 

Amido-phenylacetic  acid,  behavior  in 
the  organism,  392. 

Amido-phenylpropionic  acid,  forma- 
tion in  the  putrefaction  of  proteids, 
360  ;  behavior  in  the  organism,  391, 
392. 

Amido-succinic  acid,  see  Aspartic  acid. 

Ammonia,  formation  in  the  putrefac- 
tion of  proteids,  216  ;  from  proteid 
substances,  16,  17,  35, 36,  206,  216;  in 
trypsin  digestion,  206;  in  the  blood, 
114  ;  in  the  urine,  383. 

Ammonia,  elimination  in  disease  of  the 
liver,  383  ;  after  the  administration  of 
mineral  acids,  333  ;  after  extirpation 
of  the  liver,  352. 

Ammonia,  estimation  in  the  urine,  384. 

Ammonia  salts,  relation  to  the  forma- 
tion of  urea,  338  ;  to  the  formation  of 
uric  acid,  352. 

Ammonio-magnesium  phosphate,  in 
urinary  calculi,  432  ;  in  urinary  sedi- 
ments, 430. 

Ammonium  urate,  in  urinary  calculi, 
431  ;  in  urinary  sediments,  428. 

Amniotic  fluid,  298. 

Amphicreatin,  258. 

Amphopeptone,  26. 

Amyl-alcohol,  390. 

Amyl  nitrite,  poisoning,  115,  407. 

Amyloid,  14,  39. 

Anaemia,  111,  113;  malignant,  112. 

Anhydride  theory  of  the  formation  of 
glycogen,  140. 

Aniline,  behavior  in  the  organism,  391. 

Anisolropous  substance,  251. 

Antedouin,  325. 

Anthrax  spores,  behavior  vrith  gastric 
juice,  192. 

Antialbumose,  26. 

Antipeptoue,  26. 


INDEX. 


489 


Antimony,  passage  into  milk,  320  ;  ac- 
tion on  the  elimination  of  nitrogen, 
337. 

Antipyrin,  action  on  the  urine,  394. 

Apatite,  238. 

Arachidic  acid,  in  butter,  303. 

Arachnoid  membrane,  fluid  of,  122. 

Arbutin,  importance  in  the  formation 
of  glycogen,  189  ;  behavior  in  the  or- 
ganism, 365. 

Aromatic  combinations,  behavior  in 
the  organism,  390-394. 

Arsenic,  passage  into  milk,  320  ;  into 
sweat,  328  ;  action  on  the  elimination 
of  nitrogen,  337. 

Arsenic  acid,  action  on  pepsin  diges- 
tion, 181. 

Arseniuretted  hydrogen,  poisoning, 
160-163,  401. 

Arterin,  68. 

Ascitic  fluids,  124. 

Asparagin,  importance  in  the  synthesis 
of  proteids,  17  ;  nutritive  value,  460. 

Asparaginic  acid,  see  Aspartic  acid. 

Asparagus,  in  the  urine,  394. 

Aspartic  acid,  relation  to  the  formation 
of  urea,  338;  to  the  formation  of  uric 
acid,  352  ;  formation  from  proteids, 
17,  206,  210  ;  behavior  in  the  organ- 
ism, 389. 

Ass's  milk,  312. 

Atmid-albumin,  27. 

Atmid-albumose,  27. 

Atropin,  action  on  the  secretion  of 
saliva,  173. 

Auto-intoxication,  12. 

Bacterium  ureae,  427. 

Banting's  diet  cure,  480,  481. 

Bases,  nitrogenized  from  albumin,  17. 

Beeswax,  250. 

Benzoar  stone,  226. 

Benzoic  acid,  formation  from  protein 
substances,  17,  37,  359  ;  passage  into 
the  sweat,  328 ;  behavior  in  the  or- 


ganism, 2,  860,  392;  occurrence  in  the 
urine,  362 ;  action  on  the  exchange  of 
material,  466 ;  substituted  benzoic 
acids,  behavior  on  the  body,  392. 

Benzol,  behavior  in  the  organism,  390, 
391. 

Benzoyl  amido-acetic  acid,  see  Hippu- 
ric  acid. 

Benzoyl  chloride,  behavior  with  car- 
bohydrates, 410,  to  cystin  ;  426. 

Benzoyl  cystin,  426. 

Benzyl  alcohol,  behavior  in  the  or- 
ganism, 3. 

Bile,  143-163  ;  general  chemical  behav- 
ior, 144  ;  analyses  of  the  same,  157, 
158 ;  antiseptic  action  of,  220,  221  ; 
constituents,  144-156;  in  disease,  158  ; 
diastatic  action  of,  212  ;  action  on  the 
digestion  of  proteids,  214,  215  ;  on 
the  emulsification  of  fats,  213,  214; 
on  the  secretion  of  bile,  144  ;  on  the 
absorption  of  fat,  213,  220,  232;  on 
the  splitting  of  neutral  fats,  214  ;  on 
trypsin  digestion,  206,  215  ;  quantity, 
143 ;  passage  of  foreign  substances 
into,  158 ;  occurrence  in  the  urine, 
404,  405  ;  in  the  contents  of  the 
stomach,  193 ;  in  meconium,  224 ; 
composition,  157. 

Bile-acids,  146-150  ;  in  blood,  114,  159  ; 
pus,  130 ;  in  urine,  162,  228,  404 ; 
absorption,  228. 

Bile-acids,  Pettenkoper's  test  for, 146. 

Bile-formation,  159-163. 

Bile-pigments,  152-156  ;  origin,  160, 
161  ;  reactions,  154,  405,  406  ;  pas- 
sage into  urine,  162,  405,  406  ;  occur- 
rence in  blood-serum,  63,  114  ;  in  egg 
shells,  296. 

Bile-salts,  145,  146. 

Bile-secretion,  143. 

Bilianic  acid,  148. 

Biliary  calculi,  163. 

Biliary  fistula,  143  ;  influence  on  putre- 
faction in  the  intestines,  220. 


490 


INDEX. 


Bilicyanin,  153,  154,  156. 

Bilifulvin,  153. 

Bilifuscin,  153,  156,  163. 

Bilihumin,  153,  156. 

Biliphsein,  153. 

Biliprasin,  153,  156. 

Bilirubin,  relation  to  tbe  blood-coloring 
matters,  160,  161  ;  to  b89matoidin,  80, 
153,  160  ;  properties  and  occurrence, 
153  ;  in  urine,  405  ;  in  tbe  placenta, 
298. 

Bilirubin  calcium,  153,  163. 

Biliverdin,  properties  and  occurrence, 
155  ;  in  tbe  egg-sbell,  296  ;  in  excre- 
ments, 323  ;  in  urine,  405 ;  in  tbe 
placenta,  298. 

Bitcb's  milk,  313. 

Biuret,  839. 

Biuret  reaction,  20,  340. 

Blister-fliiid,  136. 

Blood,  54-116  ;  general  behavior,  54, 
86,  87 ;  analyses,  quantitative,  105- 
107  ;  arterial  and  venous,  68,  87,  94, 
95 ;  defibrinated,  55 ;  suffocation- 
blood,  5,  68,  87,  95  ;  quantity  in 
body,  115  ;  detection,  medico-legal, 
80  ;  behavior  in  starvation,  110,  448  ; 
composition  under  pathological  con- 
ditions, 111-115  ;  under  physiologi- 
cal conditions,  108-111;  in  iirine,  401, 
403  ;  in  contents  of  tbe  stomach,  193. 

Blood-clot,  55. 

Blood,  coagulation  of,  54,  59,  87-94. 

Blood-coloring  matters,  68-83;  in  the 

•    urine,  401. 

Blood-corpuscles,  red,  66,  67  ;  in  urine, 
401  ;  composition,  83,  106,  113  ;  col- 
orless, 84  ;  behavior  in  the  coagula- 
tion of  the  blood,  84,  90,  91. 

Blood-cylinders,  403. 

Blood,  distribution  of,  in  the  body,  116. 

Blood,  gases  of,  94^105. 

Blood-loss,  115. 

Blood-plasma,  54-62 ;  composition,  64, 
107. 


Blood-serum,  55,  63-66  ;  composition, 

64,  106. 
Blood-spots,  80. 
Blood-sweat,  338. 
Blood-tablets,  54,  84,  85  ;  importance 

in  coagulation,  91. 
Blood-transfusion,  111,  115. 
Blonds,  milk  of,  316. 
Blueberry,  coloring  matter  of,  in  urine, 

394. 
Blue  stentorin,  335. 
Bottcher's  spermine  crystals,  386. 
Bottger-Almen's  bismuth  test,  409, 

411. 
Bones  and  bone  structure,  338-343. 
Bone  earths,  338,  339. 
Bone,  softening  of,  340. 
Bonellin,  335. 
Borneo!,    behavior    in    the    organism, 

393. 
Borax,  action  on  the  exchange  of  mate- 
rial, 466  ;  on  trypsin  digestion,  306. 
Bovs^man's  disks,  251. 
Brain,  373-380. 
Bread,  behavior  in  the  stomach,  187 ; 

excrements  after  feeding  on  bread, 

330. 
Bromanil,  17. 
Bromine  combinations,  passage  into  the 

saliva,  173. 
Bromoform,  17. 
Brunner's  glands,  197. 
Brunette,  milk  of,  316. 
Brusse  mucosae,  contents  of,  127. 
Buccal  mucus,  169. 
Bufidin,  336. 
Butter-fat,  303. 
Buttermilk,  313. 

Butyric-acid,  in  contents  of  the  stom- 
ach, 193,  196;  in  the  gastric  juice, 

177  ;  in  butter- fat,  303. 
Butyric-acid  fennentation,  4,  409  ;    in 

intestines,  318. 
Butyl-alcohol,   behavior  in  the  body, 

390. 


INDEX. 


491 


Butyl-chloral,    behavior   iu   the  body, 

390. 
Byssus,  14,  39. 

Cadaverin,  376,  425. 

Caffem,48 ;  influence  on  the  elimination 
of  uric  acid,  352  ;  action  on  the  mus- 
cles, 262. 

Cairin,  action  on  the  urine,  394. 

Calcium  carbonate,  iu  urine,  332  ;  in 
urinary  calculi,  482  ;  in  urinary  sedi- 
ments, 429 ;  in  bones,  238,  239  ;  in 
tartar,  174. 

Calcium,  lack  of,  in  the  food,  241,  453 ; 
occurrence,  see  various  fluids  and  tis- 
sues. 

Calcium  oxalate,  357  ;  in  urinary  sedi- 
ments, 428  ;  in  urinary  calculi,  432. 

Calcium  phosphate,  relationship  to  the 
coagulation  of  casein,  305 ;  to  fibrin 
coagulation,  97  ;  occurrence  in  intes- 
tinal calculi,  226  ;  in  urine,  332,  384  ; 
in  urinary  sedimeut,  429  ;  in  urinary 
calculi,  432 ;  in  protein  bodies,  13,  97 ; 
in  salivary  calculi,  174. 

Calcium  sulphate,  in  urinary  sediments, 
429. 

Calories  of  the  food,  471-473  ;  various 
diateries,  474^82. 

Campherol,  393. 

Camphor,  375,  393. 

Camphor-glycuronic  acid,  375,  393. 

Cane-sugar,  behavior  vrith  intestinal 
juice,  198  ;  with  gastric  juice,  183. 

Capric  acid,  303. 

Caproic  acid,  formation  from  phenol,  6, 
390 ;  in  fatty  tissues,  243  ;  in  milk- 
fat,  303. 

Caprylic  acid,  303. 

Carbamic  acid  in  the  blood,  63. 

Carbohydrates,  importance  for  the  for- 
mation of  fat,  249,  463;  for  the  gly- 
cogen formation,  139  ;  for  muscular 
activity,  265,  268,  269 ;  exclusive  feed- 
ing on  carbohydrates,  249 ;  action  on 


the  metabolism  of  proteids,  462 ;  on 
putrefaction,  220 ;  absorption,  227, 
229,  407  ;  inadequate  supply  of,  454 
(see  various  carbohydrates). 

Carbolic  acid,  action  on  pepsin  diges- 
tion, 181  (see  Phenol). 

Carbolic  urine,  365. 

Carbon  dioxide  in  the  blood,  95,  96  ; 
in  diabetes,  104  ;  in  poisoning  -with 
mineral  acids,  176  ;  in  the  intestines, 
216  ;  in  the  Ijrmph,  118  ;  in  the  con- 
tents of  the  stomach,  189 ;  in  the 
muscles  in  activity  and  at  rest,  264, 
265,  268,  269  ;  in  rigor,  263  ;  in  secre- 
tions, 158, 170,  197,  311,  385;  in  trans- 
udations, 122  ;  binding  of  COa  in  the 
blood,  96-100;  action  on  the  elimina- 
tion of  gastric  juice,  176;  tension  in 
blood,  102,  104;  tissues,  104;  lymph. 
118;  transudation,  121,  122. 

Carbon-monoxide  blood  test,  Hoppe- 
Seyler's,  73. 

Carbon  dioxide,  elimination,  depend- 
ence of  the  external  temperature,  469; 
in  activity  and  rest,  264,  269,  467  ;  by 
the  skin,  329  ;  elimination  in  sleep  and 
waking,  468  ;  iu  various  ages,  470. 

Carbon-dioxide  haemoglobin,  74,  97. 

Carbon-monoxide  haemoglobin,  73,  76. 

Carbon-monoxide  methjemoglobin,  75. 

Carbon-monoxide  poisoning,  73,  114  ; 
action  on  the  elimination  of  nitrogen. 
337  ;  on  the  elimination  of  sugar,  407. 

Carminic  acid,  325. 

Carnin,48  ;  properties. 258  ;  in  urine,359. 

Carp,  sperm  a  of,  287. 

Cartilage,  234-238  ;  behavior  with  gas- 
tric juice,  183,  187 ;  with  pancreatic 
juice,  211. 

Cartilage  gluej  39,  234,  238. 

Casein,  origin,  300,  318,  319;  from 
woman's  milk,  313  ;  from  cow's  milk, 
304  ;  quantitative  estimation,  309  ;  re- 
lationship to  rennet,  304,  305  ;  to  gas- 
tric juice,  313. 


492 


INDEX. 


Caseoses,  27. 

Castoreum,  336. 

Castorin,  326. 

Cataract,  283. 

Cat's  milk,  312. 

Cell,  animal,  41-53  ;  nucleus,  46 ;  mem- 
brane, 43,  183. 

Cell-globulin,  58. 

Cellulose,  marsh-gas  fermentation  of, 
213,  219  ;  behavior  in  the  intestine, 
213. 

Cement,  241. 

Cephaline,  274. 

Cerebrin,  129,  274  ;  properties,  275-278. 

Cerebro-spinal  fluid,  125. 

Cerolein,  250. 

Cerotinic  acid,  250. 

Cerumen,  326. 

Cetin,  250. 

Cetyl-alcohol,  250. 

Cetylid,  276. 

Chalaza,  294. 

Charcot's  crystals,  113,  286. 

Cheese,  302,  305. 

Chenotaurocholic  acid,  148. 

Chi  tin,  323  ;  behavior  in  trypsin  diges- 
tion, 211. 

Chloral  hydrate,  behavior  in  the  body, 
375,  390. 

Chlorate,  poisoning  -with,  115,  401. 

Chlorazol,  17. 

Chlorbenzol,  behavior  in  the  body,  393. 

Chlorides,  elimination  by  the  urine,  65, 
377  ;  by  the  svreat,  328  ;  insufficient 
supply,  451 ;  action  on  the  metabolism 
of  proteids,  377,  466  (see  the  various 
fluids  and  tissues). 

Chlorocruorin,  83. 

Chloroform,  action  on  the  elimination 
of  chlorine,  377  ;  on  the  muscles,  262. 

Chlorophan,  282. 

Chlorophenyl-cystein,  393. 

Chlorphenyl-mercapturic  acid,  393. 

Chlorophyll,  325. 

Chlorosis,  112,  113. 


Chlorrhodinic  acid,  130. 

Cholalic  acid,  148 ;  relation  to  choles- 
terin,  164. 

Cholanic  acid,  150. 

Cholecyanin,  154. 

Choleglobin,  162. 

Choleic  acid,  147,  149. 

Cholera  bacillus,  behavior  with  gastric 
juice,  192. 

Cholera,  blood.  111,  112, 113,  114 ;  con- 
tents of  the  stomach,  225;  sweat,  328. 

Cholesterin,  general  chemical  proper- 
ties and  occurrence,  164 ;  in  gall- 
stones, 164  ;  in  the  brain,  274,  279  ;  in 
the  urine,  424  ;  importance  for  life- 
processes  in  the  cell,  53. 

Cholesterin  stones,  164. 

Cholesterilin,  164. 

Cholestrone,  164. 

Choletelin,  152,  155 ;  relation  to  uro- 
bilin, 370. 

Cholic  acid,  146,  148. 

Cholin,  44,  156. 

Cholohaematin,  156. 

Choloidic  acid,  150,  151. 

Chondrigen,  37,  234. 

Chondrin,  39,  234;  in  pus,  130. 

Chondrin  balls,  236. 

Cbondroitic  acid,  235,  236. 

Chondromucoid,  34,  234. 

Chorda  saliva,  168. 

Chorioidea,  283  ;  pigment,  334. 

Chkistetstsen  &  Mygge,  approximative 
estimation  of  albumin  in  the  urine, 
400. 

Chromidrosis,  328. 

Chromogens,  in  the  urine,  369  ;  in  the 
suprarenal  body,  134. 

Chrysophanic  acid,  action  on  the  urine, 
393. 

Chyle,  117,  118. 

Chylopericardium,  123. 

Chyluria,  424. 

Chyme,  186 ;  investigation  of,  193-196. 

Chymosin,  184. 


INDEX. 


493 


Cinnamic  acid,  behavior  in  the  body, 

360. 
Citric  acid,  in  milk,  304,  311. 
Coagululiou  of  blood,  54,  59,  87-94;  of 
milk,  187,  301,  302.  305;  of  muscle- 
plasma,  252,  254,  255. 
Coccygeal   glands,  secretion  of,  326. 
Cochineal,  325. 
Ccefficient,  Haser's,  387. 
Coffee,  action  on  the  exchange  of  ma- 
terial, 467. 
Collagen,  14,  37,  38;  in  connective  tis- 
sues, 233;  in  the  cornea,  237;  in  carti- 
lage, 234.  236. 
Colloid,  34,  289. 
Colloid  corpuscles,  289. 
Colloid  cysts,  289. 

Coloring  matters,  of  the  eye,  280;  of  the 
blood,  68-83;  of  blood-serum,  63;  of 
the  corpora  lutea,  288;  of  the  egg- 
shell, 296;  of  the  fat-cells,  243;  of  the 
bile,  145,  152,  156,  160,  161;  of  the 
urine,  369-374;  of  the  skin,  324,  325; 
of  the  lobster,  325  ;  of  bird-feathers, 
325;  medicinal  coloring  matters  in 
the  urine,  406. 
Colostrum,  of  woman's    milk,   315;  of 

cow's  milk,  311. 
Colostrum  corpuscles,  302,  311,  319. 
Combustion,  heat  of,  of  foods,  471-473. 
Comma    bacillus,   behavior  in  gastric 

juice,  192. 
Conchiolin,  14,  39. 
Concrements,  see  various  calculi. 
Cones  of  the  retina,  pigments  of,  282. 
Conglutin,  472. 
Cornikrystalline,  39. 
Connective  tissue.  233. 
Copaiva  balsam,  action  on  the  urine, 

894. 
Copper,  in  blood,  107;  in  hiemocyanin, 
83:  in  the  liver,  137;  in  protein  sub- 
stances, 13. 
Cornea,  237,  283. 
Cornein,  14,  39. 


Corpora  lutea,  288. 

Corpsewax,  248. 

Corpulence,  diet  cures,  480-482. 

Cow's  milk,  301-312;  general  behavior, 

301.  303;  analysis  of,  308-310:  con- 
stituents, in  organic.  310;  organic, 
304-307  ;   coagulation    with  rennet. 

302,  304;  in  stomach,  187;  composi- 
tion, 310-312. 

Cream,  312. 

Creatin,  relationship  to  the  formation 
of  urea,  257,  339;  to  muscular  activ- 
ity, 266,  268 ;  properties  and  oc- 
currence, 257;  behavior  in  the  organ- 
ism, 389. 

Creatiuiu ,  relationship  to  muscular  ac- 
tivity, 266,  268,  347 ;  properties  and 
occurrence,  347;  creatinin  zinc  chlo- 
ride, 348. 

Cresol,  363. 

Cresol-sulphuric  acid.  363,  364. 

Crotonic  acid,  423. 

Cruor,  55. 

Cruso-creatinin,  258. 

Crustaceonibin,  325. 

Crusta  iuflammatoria  or  phlogistica,  87, 
113. 

Cumic  acid,  392. 

Cuminuric  acid,  393. 

Curara  poisoniug,  action  on  the  muscles. 
264  ;  on  the  elimination  of  sugar,  407. 

Crystalbumiu,  283. 

Crystalfibrin,  283. 

Crystallin,  282. 

Crystalline  lens,  282. 

Cyanocrystallin,  296,  325. 

Cynogeu,  in  the  proteid  molecule,  4. 

Cyanuric  acid,  350. 

Cyanurin,  370. 

Cymol,  behavior  in  the  body,  392. 

Cyuurenic  acid,  377. 

Cystein,  425;  grouping  in  the  body,  393, 
425. 

Cystin  properties  and  occurrence,  425  ; 
in  the  urine,  376;  in  urinary  sediment, 


494 


INDEX. 


430  ;   in  urinary  calculi,  433  ;  in  the 

liver,  137 ;   in  the  kidneys,    876  ;   in 

sweat,  328. 
Cysts,    tapeworm,   126 ;   thyroid,    133 ; 

ovarial,  288-291. 
Cyslinuria,  376. 

Damaluric  acid,  376. 

Dumolic  acid,  376. 

Delomorphic  cell,  175. 

Density  method  of  detennining  albu- 
min, 401. 

Dentin,  239,  341. 

Dehydrocholalic  acid,  148. 

Dehydrocholeic  acid,  150. 

Desoxycholalic  acid,  148. 

Deutero-albumose,  27. 

Dextrin,  formation  from  starch,  171, 
202  ;  occurrence  in  the  contents  of  the 
stomach,  187,  in  the  muscle,  260. 

Dextrin,  substance  similar  to,  in  urine, 
374. 

Dextrose,  see  Grape-sugar. 

Diabetes  mellitus,  elimination  of  am- 
monia by  the  urine,  384;  relationship 
of  the  liver,  142,  and  the  pancreas, 
407,  to  the  elimination  of  sugar ; 
blood,  fat,  114;  amount  of  sugar,  63, 
114; urine,  general  behavior,  332,  387, 
407;  amount  of  sugar,  407;  amount 
of  COs  of  the  blood,  104;  oxybutyric 
acid  in  blood,  104  ;  in  the  urine,  423  ; 
relation  to  the  crystalline  lens,  283. 

Diabetic  sugar,  see  Grape-sugar. 

Diacetic  acid,  see  Aceto-acetic  acid. 

Diamine,  in  the  urine,  376,  425  ;  in  the 
contents  of  the  intestines,  425. 

Diastatic  enzyme,  see  Enzymes. 

Diazo-oxyacrylic  acid  ester,  37. 

Diet  for  various  classes  of  people,  474- 
482. 

Diet  cures  for  obesity,  480-482. 

Digestion,  167-232. 

Digestibility  of  various  foods,  189,  190, 
191,  476. 


Dimethyl    carbinol,    behavior   in    the 

organism,  390. 
Dimethyl-ketone,  see  Acetone. 
Dioxybenzol,  391. 
Dioxynaphthalin,  391. 
Distearyl- lecithin,  43. 
Doglingic  acid,  246. 
Donne's  pus  test,  404. 
DoREMUs's  urea  determination,  346. 
Dotterplattchen,  17,  292,  296. 
Dropsy,  112,  113. 
Dys-albumose,  27. 
Dyslysiu,  150. 
Dys-peptone,  182. 
Dyspnoea,  action  on  the  metabolism  of 

proteids,  337,  468. 

Earthy  phosphates,  elimination  by  the 
urine,  379,  384,  448 ;  solubility  in  al- 
buminous liquids,  241 ;  occurrence  in 
bone-earths,  238,  239 ;  in  concre- 
ments,  163, 174,  226,  431, 432;  in  sedi- 
ments, 429,  430  (see  various  earthy 
phosphates). 

Ebstein's  diet  cure,  480. 

Echinochrom,  83. 

Eel,  blood-serum,  64 ;  flesh,  271. 

Egg,  287;  hen's  egg,  291-298;  hatching 
of,  297. 

Egg-albumin,  see  Ovalbumin. 

Egg-globulin,  295. 

Egg,  yellow,  291. 

Ehblich's  bile-pigment  test,  406 

Eiselt's  reaction,  403. 

Elaic  acid,  245. 

Elaidic  acid,  246. 

Elaidin,  246. 

Elastin,  14,  36 ;  behavior  with  gastric 
juice,  183  ;  with  trypsin,  31J 

Elastinalbumose,  36. 

Elastinpetone,  36. 

Ellagic  acid,  227. 

Emydin,  296. 

Enamel,  of  teeth,  242. 

Encephalin,  .276,  277. 


INDEX. 


495 


Endolymph,  284. 

Energy,  potential,  of  foods,  471. 

Enzymes,  general,  8,  9,  10  ;  pancreatic 
diastase,  301;  in  blood,  142;  bile,  210; 
urine,  376  ;  muscle,  256  ;  in  secre- 
tions of  the  mucous  coat  of  intes- 
tines, 197;  in  saliva,  171;  enzymes 
m  the  mucous  coat  of  the  intestines 
which  dissolve  proteids,  197  ;  in 
urine,  376;  in  stomach,  178;  in  lower 
animals,  178;  in  pancreas,  201,  204; 
in  the  plant  kingdom,  178  ;  fat-split- 
ting enzymes,  202,  203 ;  enzj'mes  pro- 
ducing coagulation,  see  Fibrin, 
Ferment  and  Rennet ;  urea-splitting 
enzyme,  427. 

Erythrodextrin,  171. 

Erythropsin,  see  Visual  purple. 

Esbach's  albumin  determination,  400  ; 
urea  determination,  346. 

Euxanthonic  acid,  375. 

Ethal,  250. 

Ether,  action  on  blood,  67  ;  on  the  se- 
cretion of  gastric  juice,  176;  on  the 
muscles,  262;  on  the  secretion  of  pan- 
creatic juice,  201. 

Ethereal  oils,  action  on  the  muscles,  262. 

Ethereal  sulphuric  acids,  in  the  urine, 
216,  363,  391,  392;  in  sweat,  327. 

Etbidine  lactic  acid,  260. 

Ethyl-alcohol,  passage  of,  into  milk, 
320;  behavior  in  the  organism,  466  ; 
action  on  the  secretion  of  gastric 
juice,  176 ;  on  muscles,  262  ;  on  di- 
gestion, 182,  189. 

Ethyleu  lactic  acid,  260. 

Ethylenimin,  286. 

Exchange  of  material,  435-471. 

Excrements,  219,  222-224;  in  dogs 
with  biliary  fistula,  221 ;  in  starva- 
tion, 439  ;  with  various  foods,  222  ; 
elimination  of  water  with  the  excre- 
ments, 438. 

Excretin,  223. 

Excretolic  acid,  223. 


Exostose,  241. 
Extinction  coefficient,  81. 
Exudations,  117,  121. 
Eye,  280-283. 

FiBces,  see  Excrements. 

Fats,  origin  in  the  body,  247 ;  general 
properties,  detection,  and  occurrence, 
242-247;  emulsification  of  fats,  198, 
202,  203,  213,  214,  227,  244;  fat  in 
blood-serum,  62,  111,  113;  chyle, 
118  ;  yolk  of  egg,  293  ;  pus,  129;  fatty 
tissues,  242,  243  ;  bile,  156  ;  brain, 
274  ;  urine,  424  ;  bones,  239  ;  milk, 
302,  303,  310,  313,  317,  318  ;  nutri- 
tive value,  460,  461,  471-473;  ab- 
sorption, 227,  232  ;  heat  of  combus- 
tion, 471-473  ;  behavior  to  the  intes- 
tinal juice,  198  ;  to  gastric  juice,  183, 
188  ;  to  pancreatic  juice,  203  ;  saponi- 
fication of,  203,  213,  214 ;  action  on 
the  secretion  of  bile,  144. 

Fat,  metabolism  in  activity  and  at  rest, 
268,  269 ;  in  starvation,  445,  with 
various  foods,  456,  461-466,  480-482. 

Fat  cells,  183,  211,  242. 

Fat  sweat,  326. 

Fatty  acids,  general  properties,  detec- 
tion, and  occurrence,  243-247  ;  feed- 
ing with,  247  ;  nutritive  value,  461 ; 
syntheses  to  neutral  fats,  248. 

Fatty  series,  behavior  in  the  organism, 
388. 

Fatty  tissues,  242,  243;  behavior  with 
gastric  juice,  183,  188. 

Feathers,  34,  325. 

Fehling's  solution,  415. 

Fellic  acid,  150. 

Ferments,  general,  8  (see  various  fer- 
ments). 

Fermentation,  4,  8  ;  of  the  urine,  374, 
427  ;  of  the  contents  of  the  stomach, 
187,  188,  193  (see  also  various  fer- 
mentations, such  as  the  alcoholic, 
butyric  fermentations). 


496 


INDEX. 


Fermentation  lactic  acid,  properties,  oc- 
currence, etc.,  260,  261;  in  brain, 
274  ;  in  the  contents  of  the  stomach, 
188 ;  gastric  juice,  177  ;  production 
in  the  souring  of  milk,  301  ;  in  tbe 
fermentation  of  urine,  427;  detection 
in  the  contents  of  the  stomach,  194. 

Fermentation  test,  on  the  urine,  412. 

Fevers,  elimination  of  ammonia,  384  ; 
uric  acid,  352  ;  urea,  337  ;  potassium 
salts,  383  ;  blood  in  fevers,  113,  114; 
metabolism  of  proteids  in,  337. 

Fibrin,  14,  55;  properties,  57 ;  occur- 
rence in  transudations,  117,  121,  123; 
Henle's  fibrin,  285. 

Fibrin  coagulation,  58,  89-94. 

Fibrin  concrements,  226. 

Fibrin  ferment,  55,  58,  85,  89-93,   117. 

Fibrin  globulin,  59,  62. 

Fibrine,  soluble,  see  Senim-globulin. 

Fibrinogen,  14,  56,  62,  92,  117. 

Fibrinoplastic  substance,  see  Serum 
globulin. 

Fibroin,  14,  39. 

Fish,  egg,  18.  296  ;  bones,  240 ;  scales, 
50  ;  air-bladder,  50. 

Flesh,  amount  of  nitrogen  in,  272,  441; 
digestibility,  187,  190  ;  composition, 
270,  271  (see  also  Muscle). 

Flesh,  metabolism  of,  in  starvation, 
445  ;  in  various  foods,  454-465. 

Flesh  accumulation  of,  with  various 
foods,  454,  455,  462,  463. 

Fluorine,  in  bones,  238,  339;  in 
enamel,  242. 

Fly-maggots,  formation  of  fat  in,  248. 

Formic  acid,  in  butter,  303  ;  in  con- 
tents of  the  stomach,  196 ;  passage 
into  the  urine,  374. 

Frog's  eggs,  membrane  of  the  same,  82. 

Fumaric  acid,  17. 

Fundus  glands,  175,  185. 

Furfurol,  relation  to  Pettenkofer's 
test  for  bile  acids,  146  ;  behavior  in 
the  body,  389. 


Furfuracrylic  acid,  389. 
FiJRBRiNGER's  albumin  reagent,  397. 
Fuscin,  282. 

Gralactose,  306;  from  cerebrin,  377;  from 
vegetable  bodies,  320. 

GaXiLois's  inosit  test,  259. 

Gases  of  the  blood,  94-105;  of  the  con- 
tents of  the  intestine,  218  ;  of  the  bile, 
158  ;  of  the  urine,  385 ;  of  the  hen's 
egg,  296  ;  of  the  chyle,  118  ;  of  milk, 
311  ;  of  muscles,  262,  264  ;.  of  transu- 
dations, 112. 

Gas,  exchange  of,  -with  various  ages, 
470  ;  by  the  skin,  328  ;  in  starvation, 
446 ;  in  various  conditions  of  the 
body,  467,  468  ;  in  the  muscles,  264 ; 
with  various  foods,  447. 

Gastric  juice,  175 ;  secretion  of,  176 ; 
degree  of  acidity,  194 ;  artificial  gas- 
tric juice,  179;  action,  23,  26,  38, 
179-184,  186-192. 

Gelatine,  38  ;  importance  in  the  forma- 
tion of  glycogen,  139 ;  putrefaction, 
37,  216;  nutritive  value,  459;  behavior 
with  gastric  juice,  183,  211 ;  to  pan- 
creatic juice,  211. 

Gelatine,  forming  tissues,  see  CoUogen. 

Gelatine  peptone,  38. 

Generative  organs,  285-299. 

Germ,  of  the  egg,  291. 

Globulins,  14;  general  character,  22; 
in  the  urine,  397,  400;  in  the  proto- 
plasm, 42  (see  various  globulins). 

Globulin  tablets,  86. 

Globuloses,  27. 

Glucosamine,  323. 

Glucose,  formation  by  the  action  of 
saliva,  171 ;  of  pancreatic  juice,  202 
(see  Grape-sugar). 

Glue  sugar,  see  Glycocoll. 

Glutamic  acid,  16. 

Glntin,  in  pus,  130  (see  Glue). 

Glycerin,  importance  for  the  formation 
of  glycogen,  139,  140;  relationship  to 


INDEX. 


497 


the  synthesis  of  fats,  248 ;  action  on 
the  elimination  of  uric  acid,  351; 
solvent  for  enzymes,  9 ;  nutritive 
value,  462. 

Glycero-pbosphoric  acid,  43,  113,  127, 
131,  134,  156;  in  the  urine,  374,  376. 

Glycin,  see  Glycocoll. 

Glycocholic  acid,  145;  properties,  146; 
quantity  in  excrements,  219  ;  in  vari- 
ous animal  bile,  158  ;  behavior  in  the 
putrefaction  in  the  intestines,  219. 

Glycocoll.  properties,  150 ;  production 
in  the  putrefaction  of  gelatine,  37, 
216  ;  from  protein  substances,  37-39; 
relation  to  the  formation  of  uric  acid, 
350,  353 ;  to  the  formation  of  urea, 
338,  339  ;  syntheses  with  glycocoll, 
3,  160,  359,  389,  392. 

Glycogen,  138-143;  origin,  139;  gen- 
eral chemical  behavior,  138,  139 ; 
relation  to  the  formation  of  sugar, 
141,  142  ;  to  muscular  activity,  265- 
268  ;  to  rigor  mortis,  263 ;  occurrence 
in  the  muscles,  2i50;  in  the  protoplasm 
42,  52,  85. 

Glyconic  acid,  374. 

Glycosuria,  63,  142,  407. 

Glycuronic  acid,  properties,  374;  paired 
glycuronic  acids,  217,  367,  374 ; 
grouping  in  the  body,  390,  393  ; 
origin,  390. 

Glycuron,  374. 

Glyoxyldiureid,  358. 

Gmelin's  test  for  bile  pigments,  154; 
in  the  urine,  405. 

Goat  milk,  312. 

Gout,  elimination  of  uric  acid  in,  351, 
352. 

Graaffian  vesicles,  287. 

Grape-sugar,  properties  and  occurrence, 
406-409  ;  in  urine,  63,  142.  406-419  ; 
detection,  410-414;  quantitative  esti- 
mation, 414-419  ;   reactions,  408-410. 

Guaiacum  blood  test,  402. 

Guanin,  properties  and  occurrence,  50; 


in  urine,  359  ;  quantity  in  liver,  137; 

pancreas,  200  ;   spleen,  287. 
Guanin  gout,  51. 
Guanin  lime,  50. 
Guano,  49,  50,  351. 
Guano  biliary  acids,  147. 
Guanovulit,  296. 
Gum,  animal,  32  ;  in  urine,  374. 

Hsemin,  78,  79. 

Hsemin  crystals,  79,  403. 

Haemochromogen,  69  ;  properties,  76  ; 
in  muscle,  256. 

Haemocyanin,  83. 

Haemoglobin,  properties  and  behavior, 
72;  quantity  in  blood,  69,  108-111; 
quantitative  estimation,  82  ;  behavior 
in  the  trypsin  digestion,  211  (see 
Oxy haemoglobin  and  its  combinations 
with  other  gases). 

Haemoglobiuuria,  401. 

Haemometer,  82. 

Haematocrystallin,  see  Oxyhaemoglo- 
bin. 

Hair,  34  ;  ash,  322  ;  pigments  of,  334. 
325. 

Hair-balls,  226. 

Haser's  coefficient,  387. 

Haematin,  relation  to  bilirubin,  161  ;  to 
urobilin,  161,  371  ;  properties,  76. 

Haematinometer,  81. 

Hsematochlorin,  298. 

Haematogen,  292,  297. 

Haematoglobulin,  see  Oxybgemoglobin 

Haematoidin,  relation  to  bilirubin,  80. 
153,  160,  163  ;  properties,  80  ;  occur- 
rence, Corp.  lutea,  288 ;  in  excre- 
ments, 223  ;  sediments,  430. 

Haematolin,  78. 

Haematoporphyrin, relation  to  bilirubin, 
78,  161  ;  to  urobilin,  371 ;  properties, 
78  ;  occurrence  in  loM'er  animals,  325. 

Haeraatosiderin,  162. 

Hsematuria,  401. 

Haemerythrin,  83. 


498 


INDEX. 


Heat,  action  on  the  exchange  of  ma- 
terial, 469;  development  of  heat  in 
plants,  2. 

Heller's  albumin  test,  19;  in  urine, 
396. 

Heller-Teichm ANN'S  blood  test,  403. 

Hemi-albumose,  26. 

Hemi-collin,  38. 

Hemi-elastin,  36. 

Hemi-peptone,  26. 

Hemp-seed  stone,  482. 

Hen's  egg,  291-298;  hatching,  297. 

Heteroalbumose,  27. 

Heteroxanlhiu,  48,  359. 

Hippomelanin,  324. 

Hippuric  acid,  359;  properties  and  re- 
actions, 361;  formation  in  the  body, 
3,  360,  361,  392;  splitting,  360,  362; 
occurrence,  360;  in  sediments,  430. 

Histozyme,  363. 

Hoemann's  tyrosin  test,  309. 

Holothuria,  Mucin,  34. 

Homocerebin,  276,  277. 

Hoppe-Seyler's  carbon  monoxide  test, 
73;  xanthin  test,  49. 

Horn,  35. 

Horn  substance,  see  Keratin. 

Horse's  milk,  312. 

Humin  substance,  369,  394. 

Humor,  aqueous,  126. 

Huppert's  bile-pigment  reaction,  154, 
405. 

Hyaline,  34,  323. 

Hyaline  substance  of  Rovida,  67,  85, 
129. 

Hyalogen,  14,  34. 

Hydracrylic,  260. 

Hydraemia,  112. 

Hydramnion,  299. 

Hydrobilirubin,  152,  156 ;  relation  to 
urobilin,  161,  228,  370  ;  formation  in 
putrefaction,  219. 

Hydrocele  fluid,  125. 

Hydrochinon,  365,  394. 

Hydrochinon  sulphuric  acid,  363,  365. 


Hydrocinnamic  acid,  behavior  in  the 
body,  360. 

Hydrochloric  acid,  secretion  by  the 
stomach,  176 ;  anti-fermentive  ac- 
tion, 192 ;  action  on  opening  the  py- 
lorus, 189  ;  on  the  secretion  of  pepsin, 
177  ;  quantity  of,  in  the  gastric  juice, 
177  ;  reagents  for  free  HCl,  194,  195  ; 
action  on  albumin,  20,  23,  180. 

Hydrocyanic  acid,  action  on  pepsin  di- 
gestion, 181;  on  trypsin  digestion,206. 

Hydrogen,  in  putrefactive  and  fermen- 
tive  processes,  4,  216,  218. 

Hydrogen  peroxide,  in  urine,  385. 

Hydrolytic  splitting,  8. 

Hydronephrosis  fluid,  331. 

Hydroparacumaric  acid  in  putrefac- 
tion in  the  intestines,  216. 

Hydrophenoketon,  6. 

Hydrops  folliculorum  Graafii,  288. 

Hyo-glycocholic  acid,  147. 

Hypalbuminose,  113. 

Hyperalbuminose,  113. 

Hyperinose,  113. 

Hypinose,  113. 

Hyposulphites,  in  the  urine,  376, 

Hypoxanthin,  relation  to  the  formation 
of  uric  acid,  352,  389  ;  properties, 
etc.,  50  ;  quantity  in  the  liver,  187 ; 
in  muscles,  256 ;  pancreas,  200 ; 
semen,  287. 

Iceterus,  143,  163;  blood,  114;  in  urine, 

405. 
Ichthidin,  396. 
Ichthin,  296. 
Ichthulin,  296. 
Indican,  366-368. 
Indican  elimination  in  starvation,  319, 

366;  in  disease,  366. 
Indigo,  366;  in  sweat,  338. 
Indigo  blue,  367,  370. 
Indol,  properties,  318;  formation  from 

proteids,    16,    17;    in     putrefaction, 
'     316,  217,  363,  366. 


INDEX. 


499 


Indophenol  blue,  behavior  in  the  tis- 
sues, 5. 

Indoxyl,  216,  366. 

Indoxyl  glucoronic  acid,   366,  367,  393. 

ludoxyl  red,  367. 

ludoxyl  sulphuric  acid,  363,  366,  367. 

Inosit,  properties  and  occurrence,  356; 
in  urine,  420. 

Inosinic  acid,  256. 

lutestiue,  contents,  212-225. 

Intestine,  putrefaction  processes  there- 
in, 215-222;  absorption,  215,  216, 
225,  227-232;  digestive  processes, 
212-216. 

Intestine,  glands  of  the  mucous  mem- 
brane, 197. 

Intestinal  calculi,  226. 

Intestinal  fistula,  197. 

Intestinal  gases,  218. 

Intestinal  juice,  197, 198. 

Iodine  combinations,  passage  of,  into 
milk,  320;  sweat,  328;  saliva,  173. 

Iodoform  test,  Gunning's,  421;  Lik- 
ben's,  421. 

Ischuria,  328. 

Isodynamic  value  of  foods,  473. 

Isocholesterin,  165. 

Isotropous  substance,  251. 

Iron  in  blood-coloring  matters,  70,  76, 
77,  81.  161;  in  blood,  63,  65,  106;  in 
the  bile,  157.  161;  in  urine,  385;  in 
the  liver,  136,  137;  in  milk,  310,  315, 
320;  in  the  spleen,  130,  131,  136;  in 
muscles  262;  in  protein  substances, 
15,  23,  130,  136;  elimination  of  iron, 
157,  161.  174.  385;  amount  of  iron  in 
dog's  milk  and  new-born  dogs,  317; 
absorption.  453. 

Iron  salts,  elimination  bv  the  urine.  385; 
action  on  the  blood,  111;  on  trypsin 
digestion,  206;  absorption.  453. 

Jaffe's  indican  test,  867;  creatinin  re- 
action, 349. 
Janthinin,  325. 


Jaune  indien,  375. 

Jecorin,  properties  and  occurrence,  137. 

Kephir,  307. 

Kerasene,  276. 

Keratin,  14,  322;  properties,  34;  in 
egg-shells,  296;  in  bones,  238;  be- 
havior with  gastric  juice,  183;  to 
pancreatic  juice,  211. 

Keratiuose,  35. 

Kidneys,  331 ;  relation  to  the  formation 
of  uric  acid,  352;  to  urea,  339;  to  hip- 
puric  acid,  361. 

Kjeldahl's  method  of  determining  ni- 
trogen, 341,  345. 

Knapp's  titration,  method,  417. 

Knop-Hufner  method  for  determin- 
ing urea,  346. 

Kumyss,  307. 

Kyestem,  430. 

Lactalbumin,    14;    properties,    306;    in 

human  milk,  313. 
Lactates,  261. 
Lactic   acid,   260  (see  Paralactic  acid 

and  Fermentation  lactic  acid). 
Lactic  acid,  fermentation,  307,  409;  in 

urine,  427;  in  stomach,  187,  188;  in 

milk,  301. 
Lacto- caramel,  307. 
Lacto-globulin,  306. 
Lacto-protein,  306, 
Lactose.  306. 
Lsevulinic  acid,  32. 
Latebra,  291. 
Laxatives,  action  on  the  blood,  113;  on 

the  secretion  of  intestinal  juice,  197 

action  of,  225. 
Lead,  in  blood,  107;  in  the  liver,  137 

passage  into  the  milk,  320. 
Lecithin,  properties  and  occurrence,  43 

action    on    the    coagulation    of    the 

blood,  92;  putrefaction  of,  45,  219 

relalion  to  muscular  activity,  266. 
Lens,  see  Crystalline  lens. 


500 


INDEX. 


Lens  capsule,  282. 

Lethal,  250. 

Leucaemia,  48,  113  ;  elimination  of  urea, 
352;  xanthin  bodies,  48,  113,  182, 
359. 

Leuceines,  16. 

Leucin,  16,  17,  206;  relationship  to 
the  formation  of  uric  acid,  352; 
to  the  formation  of  urea,  338,  389  , 
preparation,  209  ;  properties,  occur- 
rence, etc.,  206 ;  passage  into  the 
urine,  424 ;  behavior  in  the  body,  338, 
389. 

Leucinimid,  17. 

Leucocytes,  see  Colorless  blood-corpus- 
cles. 

Leucomaines,  12 ;  in  urine,  376. 

Levulose  in  urine,  419. 

Lieberkuhn's  glands,  197. 

Liebig's  titration  method  for  estimating 
the  quantity  of  urea,  341. 

Ligamentum  nuchse,  36. 

Lime,  lack  of,  in  foods,  241,  453. 

Linseed  oil,  feeding  with,  347. 

Lipacidaemia,  114. 

Lipsemia,  113. 

Lipochrome,  63,  393. 

Lipuria,  424. 

Lithium  in  blood,  107. 

Lithobilic  acid,  227. 

Lithofellic  acid,  227. 

Lithuric  acid,  377. 

Liver,  135-137  ;  relationship  to  the 
formation  of  uric  acid,  352,  353  ;  to 
the  formation  of  urea,  338,  339;  blood 
of  the  liver,  108,  141 ;  albuminous 
bodies,  136 ;  fat  of,  136 ;  amount  of 
sugar,  141. 
Liver,  atrophy,  acute  yellow,  secretion 
of  ammonia,  338,  384  ;  of  urea,  338, 
384 ;  leucin  and  tyrosin,  424  ;  lactic 
acid,  260,  374. 
Liver,  cirrhosis,  ascitical  fluids,  124  : 
action  on  the  elimination  of  ammonia 
and  urea,  338,  384. 


Liver  extirpation,  elimination  of  am- 
monia, 352  ;  of  uric  acid,  352  ;  lactic 
acid,  352,  373  ;  action  on  the  forma- 
tion of  bUe,  159,  160. 

Luteines,  293  ;  in  corpora  lutea,  288 ; 
in  yolk  of  the  egg,  293  ;  in  serum,  63; 
relationship  to  hsematoidin,  80,  288. 

Lymph,  117-121.' 

Lymphatic  gland,  130. 

Lymph  fibrinogen,  85. 

Lymph-cells,  proteids,  42  see  (Color- 
less blood-corpuscles). 

Mackerel  flesh,  271. 

Madder  in  urine,  393. 

Magnesium  in  the  urine,  384  ;  in  bones, 
238,  239  ;  in  muscles,  262,  270  (see 
various  tissues  and  fluids). 

Magnesium  phosphate,  in  intestinal  cal- 
culi, 226  ;  in  urine,  393  ;  in  urinary 
calculi,  431,  432 ;  in  urinary  sedi- 
ments, 430  ;  in  bones,  338,  239. 

Malaria,  blood  in,  113. 

Malt  diastase,  171. 

Maltose,  formation  from  starch,  171,. 
202  ;  behavior  to  intestinal  juice,  198, 
213. 

Mammary  glands,  300,  319,  330. 

Mandelic  acid,  393. 

Mare's  milk,  312. 

Margarin  and  margaric  acid,  245. 

Marsh-gas,  in  intestine,  218,  219  ;  in 
intestinal  putrefaction,  216  ;  in  the 
fermentation  of  cellulose,  213,  218  ; 
by  the  decomposition  of  lecithin,  219. 

Material,  exchange  of,  dependence  on 
the  external  temperature,  469  ;  in 
various  ages,  470 ;  in  activity  and 
rest,  264-270,  467,  468;  in  various* 
sexes,  470  ;  in  starvation,  443-449  ; 
with  various  foods,  454-^65  ;  in  sleep 
and  waking,  468  ;  calculation  of  the 
extent  of  exchange  of  material,  441, 
442. 

Meconium,  224. 


INDEX. 


601 


Melanin,  relation  to  blood-coloring 
matters,  163,  324  ;  properties,  occur- 
rence, and  composition,  324,  325;  in 
the  eye,  282  ;  in  the  urine,  403. 

Melanaemia,  114. 

Melauogen,  403. 

Melanotic  tumor,  coloring  matters  of, 
324. 

Melissyl  alcohol,  250. 

Mellitaemia,  114. 

Menstrual  blood,  109. 

Menthol,  behavior  in  the  body,  393. 

Mercapturic  acid,  393. 

Mesitylen,  behavior  in  the  body,  392. 

Mesitylenic  acid,  392. 

Mesitylenuric  acid,  393. 

Metalbumin,  289. 

Metallic  salts,  action  on  enzymotic  pro- 
cesses, 173,  181,  206. 

Metaphosphoric  acid,  constituents  of 
the  nucleins,  23,  46 ;  albumin  rea- 
gent, 19  ;  in  urine,  396. 

Methal,  250. 

Methaemoglobin,  74 ;  in  blood  in  pois- 
oning, 115  ;  in  urine,  401. 

Methyl-guanidin,  348. 

Methyl-guanidin  acetic  acid,  see  Crea- 
lin. 

Methyl-glycocoll,  see  Sarkosin. 

Methyl-hydantoin,  350. 

Methyl  hydantoinic  acid,  389. 

Methyl-indol,  see  Skatol. 

Methylpyridyl-ammonium  hydroxy  1, 
393. 

Methyl-uric  acid,  350. 

Methyl-uramin,  348. 

Micrococcus  urese,  437. 

Micro-organisms  in  the  intestinal  canal, 
10,  215. 

Milk,  300-322;  secretion,  318-322;  blue 
or  red  milk,  321;  milk  in  disease, 
320;  passage  of  foreign  bodies  into, 
320  (see  various  varieties  of  milk). 

Milk- fat,  303;  analysis,  309;  formation, 
319. 


Milk-globules  of  cow's  milk,  302,  303; 
of  human  milk,  313. 

Milk,  human,  312-316;  behavior  in 
stomach,  187,  313;  composition,  314. 

Milk-plasma,  304. 

Milk-sugar,  properties,  306,  307;  fer- 
mentation, 187,  301,  307;  quantita- 
tive estimation,  308,  310;  passage  into 
the  urine,  307,  419;  origin,  320. 

Mineral  acids,  104,  333,  450,  452;  anti- 
fermentive  action,  193;  action  on  the 
elimination  of  ammonia,  333,  453. 

Mineral  bodies,  elimination  in  starva- 
tion, 448;  inadequate  supply  of,  449; 
behavior  in  the  organism,  450  (see 
various  fluids,  tissues,  and  juices). 

Millon's  reagent,  20. 

Mohb's  titration  method  for  chlorine, 
378. 

Mooke's  sugar  test,  408. 

Morphine,  passage  into  milk,  320;  into 
urine,  393. 

Mucic  acid,  306. 

Mucin,  14;  properties  and  composition, 
33;  in  connective  tissue,  233;  in 
urine,  376,  395;  in  salivary  glands, 
32,  168;  detection,  401. 

Mucin-like  bodies  in  bile,  145;  urine, 
376,  395;  kidneys,  331;  thyroid  gland, 
133;  synovial  fluid,  126. 

Mucinogen,  32. 

Mucinoid,  14,  31,  34. 

Mucoid,  14,  31,  34;  in  ascitical  fluids. 
124;  cornea,  237;  vitreous  humor, 
234,  282. 

Mucous  tissues,  234. 

Mucus,  of  the  bile,  144;  of  the  urine, 
331,  376,  401;  of  the  synovia,  126. 

Mulberry  calculi,  433. 

Murexid  test,  354. 

Muscles,  non-striated,  372;  striated, 
251-272;  blood  of  the  same,  109.  264. 
265,  268;  chemical  processes  in 
activity  and  at  rest,  264-270;  in  rigor 
mortis,  263;  albuminous  bodies,  253- 


502 


INDEX. 


256;    extractives,    256-261;    coloring 

matters,  256;  fat,  261,  268,  270,  271; 

gases,  262,  264-268;  miaeral  bodies, 

261,  262,  270;  reaction,  251,  252,  266; 

amount  of  water,  272;  composition, 

270. 
Muscle-coloring  matters,  256. 
Muscle-fibre,  253. 
Muscle-plasma,    252  ;    coagulation    of, 

252,  254,  263,  272. 
Muscle-serum,  252. 
Muscle-sugar,  260. 
Muscle-stroma,  255. 
Muscle-syntonin,  256. 
Muscular  activity,  chemical  processes 

in  the  muscles,  264-270 ;   action  on 

the  urine,  333,  347;  on  the  exchange 

of  material,   264-270,  467,  468,  478, 

479. 
Musculin,  14  ;  properties,  255. 
Mutton  tallow,  247. 
Myeline,  274. 
Myeline  forms,  274. 
Mygge  and   Chkistensen's   albumin 

determinate,  400. 
Myoalbumin,  255. 
Myoalbumose,  255. 
Myosin,  252  ;  properties,   253,   254  ;  in 

protoplasma,  43,  84. 
Myosin-ferment,  254. 
Myosinogen,  254. 
Myosin  OSes,  37. 
Myoglobulin,  255. 
Myohsematin,  256. 
Myricyl  alcohol,  350. 
Myrisin,  350. 

Myristinic  acid  in  butter,  303. 
Myxoederma,  133. 
Myxoid  cyst,  288. 

Nails,  34,  35,  322. 

Naphthalin,  changing  of  the  urine,  394 ; 

behavior  in  the  body,  394. 
Napthol,  reagent  for  sugar,  410,  414; 

behavior  in  the  Body,  394. 


Naphthol  glycuronic  acid,  313,  393. 

Navel-cord,  mucin  of,  32,  234. 

Nebecula,  381. 

Neossin,  34. 

Nerves,  273. 

Neuridin,  278,  291. 

Neurin,  44 ;  in  supra-renal  body,  134. 

Neurokeratin,  35,  273,  280. 

Neutral  fats,  see  Fats. 

Nitrates  in  urine,  383. 

Nitric-oxide  haemoglobin,  74. 

Nitrobenzoic  acid,  17. 

Nitrobenzyl-alcohol,  393. 

Nitrogen,  elimination  in  rest  and  activ- 
ity, 267-270,  467,  468;  in  starvation, 
444,  445 ;  with  various  foods,  454-465; 
elimination,  by  the  excrement,  440 ; 
urine,  337,  338,  380,  383,  438,  439,  440 ; 
horn-formation,  439,  440  ;  sweat,  439; 
relation  to  the  elimination  of  phos- 
phoric acid,  380;  to  sulphuric  acid, 
338. 

Nitrogen,  free,  in  blood,  94;  in  intestines, 
218;  in  stomach,  189  ;  in  secretions, 
158,  170,  311,  385;  in  transudations, 
123;  combined  nitrogen,  quantity  of, 
in  the  discharges  of  the  intestines,  440 ; 
in  meat,  272,  441  ;  in  urine,  337,  338; 
determination,  341-347 ;  in  protein 
substances,  15,  32,  35,  39. 

Nitrogen  deficit,  439. 

Nitrogenous  equilibrium,  440;  with  va- 
rious foods,  454-465. 

Nitrophenyl-propiolic  acid,  reagent  for 
sugar,  410,  414 ;  behavior  in  the 
body,  366,  367. 

Nitrosoindol-nitrate,  217. 

Nitrotoluol,  behavior  in  the  body,  393. 

Nitrotyrosin-nitrate,  309. 

Non-striated  muscles,  272. 

Nuclein,  properties  and  occurrence, 
46;  in  blood-corpuscles,  67;  pus,  129  ; 
brain,  273  ;  sperma,  287. 

Nuclein  protamiu,  287. 

Nucleoalbumin,  14;  properties,  32;  in 


INDEX. 


503 


bile,  145;  in  urine,  376,  396;  kidneys, 
331  ;  mammary  glands,  300,  319;  sy- 
novia, 126. 

Nutritive  bodies,  necessary,  435 ;  heat 
of  combustion  of,  471-473. 

Nutrition,  need  of  man  for,  473-480. 

Nutrition,  influence  on  the  secretion  of 
intestinal  juice,  J97  ;  bile,  143,  144  ; 
gastric  juice,  176  ;  pancreatic  juice, 
200.  oii  the  elimination  of  ammonia, 
384  ;  uric  acid,  351 ;  urea,  337,  454, 
462,  465  ;  carbon  dioxide,  447 ;  min- 
eral bodies,  337,  379,  382  ;  on  the  ex- 
change of  material,  449-465  ;  various 
foods  rich  in  proteids,  454-460 ;  pro- 
teid  and  fat,  460-462  ;  proteid  and 
carbohydrates,  462-465  ;  insufficient, 
449-454. 

Nylander's  test  for  sugar,  411. 

Odoriferous  bodies  in  urine,  394. 

CEdema,  fluid  of,  126 

Ortel's  diet  cure,  480,  481. 

Oleic  acid,  245. 

Olein,  243-245. 

Oligmia,  112. 

Oligocythsemia,  113. 

Oliguria,  387. 

Olive-oil,  action   on  the    secretion   of 

bile,  144. 
Onuphin,  34. 
Oocyan,  396. 
Oorodein,  396. 

Oy^ium,  passage  into  the  milk,  330. 
Optogram,  383. 
Ornithin,  389,  893. 
Ornithuric  acid,  392. 
Organs,  loss  of  weight  in  starvation, 

448. 
Organic  acids,  behavior  in  the  body, 

389. 
Organized   proteids  or  tissue-proteids, 

457,  458. 
Orthonitrophenyl-propiolic     acid,     see 

Nitrophenyl-propiolic  acid. 


Ossein,  37,  238,  240. 

Osteomalacia,  241  ;  lactic  acid  in  urine, 
374. 

Otholiths,  284. 

Ovalbumin,  14 ;  properties,  295 ;  be- 
havior in  the  body,  284. 

Ovarial  cysts,  288-291. 

Ovovitellin,  14  ;  properties,  292. 

Ovum,  287. 

Oxalic  acid,  in  blood,  114  ;  in  urine, 
357  ;  behavior  in  the  body,  389. 

Oxalic-acid  diathesis,  357. 

Oxalate  lime  in  urine,  357 ;  calculi, 
432  ;  sediments,  428. 

Oxalate  stone,  432. 

Oxiiluric  acid,  251,  357. 

Oxaluria,  357. 

Oxamid,  16. 

Oxidation,  1-5,  71,  94,  95,  96,  155,  216, 
217,  350,  363,  389,  391,  392. 

Oxyacids,  formation  of,  in  putrefac- 
tion, 216;  passage  of,  into  the  urine, 
216,  368;  in  sweat,  327. 

Oxybenzoic  acid,  grouping  in  the 
body,  392. 

Oxybenzol,  391. 

Oxybutyric  acid,  in  blood,  104;  in 
urine,  384,  433. 

Oxygen,  activity  of.  in  the  animal  body, 
5,  71,  95;  in  blood,  95,  96,  100,  101, 
102;  in  intestines,  158,  170;  lymph, 
118;  in  stomach,  189;  in  transuda- 
tions, 133;  binding  of  the  oxygen  in 
the  blood,  70,  95;  tension  of,  in  the 
blood,  100,  101;  in  the  expired  air,. 
101. 

Oxygen,  consumed  in  activity  and  rest, 
265,  468;  in  starvation,  446;  by  the 
skin,  338. 

Oxyhaematin,  76. 

Oxyhaemocyanin,  83. 

Oxyhaemoglobin,  69;  dissociation  of, 
70,  100;  properties  and  behavior,  69- 
71;  quantity  in  blood,  69,  lO'^-lU; 
in  muscle,  256;  passage  into  the  urine. 


504 


INDEX. 


401;  behavior  with  gastric  juice,  183; 

to  trypsin,  211. 
Oxynaphthalin,  391. 
Oxynitroalbumia,  17. 
Oxyphenylamido-propionic    acid,    see 

Tyrosin. 
Oxyproto-sul phonic  acid,  17. 
Ozone,  3,  96. 
Ozone-exciter,  96. 
Ozone- transmitter,  7i. 

Palmitic-acid,  245. 

Palmitic-acid  cetyl-ether,  250. 

Palmitic-acid  melissyl-ether,  250. 

Palmitin,  243,  245. 

Pancreas,  199,  200;  extirpation,  action 
on  the  elimination  of  sugar,  407; 
cbarge,  132  ;  change  during  secretion, 
199,  211,  212. 

Pancreatic  juice,  200 ;  secretion,  200, 
201,  211,  212  ;  enzymes,  202-206;  ac- 
tion on  nutritive  bodies,  303-206,  314, 
315. 

Para-amido-phenol,  391. 

Parabaraic  acid,  351. 

Paracasein,  305. 

Paracresol,  formation  in  putrefaction, 
316,  363. 

Paraglobuliu,  see  Serum-globulin. 

Parahsemoglobin,  71. 

Paralactic  acid,  relation  to  uric  acid, 
350,  351;  properties  and  occurrence, 
260  ;  production  in  muscle  during 
activity,  266,  268  ;  in  rigor  mortis, 
263  ;  in  osteomalacia,  241  ;  passage 
of,  into  the  urine,  352,  374. 

Paralbumin,  289,  390. 

Paramyosin,  253,  255. 

Paraoxyphenyl-propionic  acid,  316,  369. 

Parapeptone,  182. 

Paraphenyl-acetic  acid,  216,  368. 

Paraxanthin,  48,  359. 

Parietal  cells,  175. 

Parotid,  167. 

Parotid  saliva,  169,  170. 


Parovarial  cysts,  291. 

Peutacumin,  325. 

Pentamethylendiamin,  376. 

Pepsin,  175,  178;  properties,  178;  in 
urine;  228,  376;  in  muscles,  356;  de- 
tection in  the  contents  of  the  stom- 
ach; 193;  quantitative  estimation,  180, 
181;  action  on  albumin,  179;  on  other 
bodies,  183. 

Pepsin  digestion,  179,  180,  181,  183; 
products  of  the  same,  36-39. 183^  183 
186. 

Pepsin-glands,  175. 

Pepsin  test,  180. 

Pepsin  hydrochloric  acid,  183. 

Pepsinogen,  186. 

Peptone,  25;  in  the  putrefaction  of  pro- 
teids,  316;  in  pepsin  digestion,  37, 
183;  in  trypsin  digestion,  37,  306;  as- 
similation, 331,  332;  preparation,  39; 
nutritive  value,  459;  absorption,  337- 
333;  passage  into  the  urine,  338,  398. 

Peptone-plasma,  54. 

Peptonuria,  398. 

Pericardial  fluid,  133,  133. 

Perilymph,  384. 

Peritoneal  fluid,  132,  124. 

Perspiratio  insensibilis,  438. 

Pettenkofer's  test  for  bile-acids,  146. 

Phacozymas,  283. 

Phaseomannit,  258. 

Phenaceturic  acid,  362,  393. 

Phenol,  elimination  by  the  urine,  216, 
363;  in  starvation,  219;  estimation  in 
urine,  364;  action  on  the  urine,  394; 
electrolysis  of,  6,  390;  formation  in 
putrefaction,  316,  363;  behavior  in 
the  body,  316,  263,  393,  394. 

Phenol  glycuronic  acid,  364,  393. 

Phenol-sulphuric  acid  in  urine,  363, 
364,  393;  in  sweat.  337. 

Phenyl  acetic  acid,  formation  in  putre- 
faction, 316;  in  body,  391,  392. 

Phenyl-amido-acetic  acid,  392 

Phenyl-amido-propionic  acid,  391,  392. 


INDEX. 


505 


Phenyl-glucosazone,  410. 
Pbenylhydiaziae  test.  307;   in  urine, 

410,  413. 
Pheayl-lactosazone,  307. 
Piienyl-propionic    acid,  formation    in 

putrefaction,  216,  361;  in  body,  393. 
Phlebin,  68. 

Phloridzin  diabetes,  143,  407. 
Phosphorus-poisoning,    action    on   the 

elimination  of  ammonia,  338,  384;  of 

urea,  337,  338,  384;  lactic  acid,  374; 

production  of  fatty  degeneration,  248; 

chauging  the  urine,    337,    338,   374, 

424. 
Phosphorized  compounds  in  urine,  376. 
Phosphoric    acid,   elimination    by  the 

urine,    379-382,    448;    formation    in 

muscular  activity,  266,  268. 
Phosphates  in  urine,  379-382,  395  (see 

various  phosphates). 
Phosphate  diabetes,  380. 
Phosphate  stone,  432. 
Phenosin,  276. 
Phthalic  acid,  391. 
Phymatorusiu,  324;  in  urine,  403. 
Physetoleic  acid,  250. 
Picric  acid,  reagent   for  albumin,  20, 

400;    for  creatinin,   349;    for  sugar, 

410,  414. 
Pig-milk,  313. 
Pike,  flesh  of,  272. 
Pilocarpin,  action  on  the  secretion  of 

intestinal    juice,     197;    sweat,    337; 

saliva,  173. 
Piria's  tyrosin  test,  208. 
Placenta,  298. 
Plants,  chemical  processes  in  the  same, 

1,  2. 
Plasma,  see  Blood-plasma. 
Plasmoschise,  92. 
Pleural  fluid,  123. 
Plums,  influence  on  the  elimination  of 

hippuricacid,  360,  361. 
Polycythsemia,  111,  116. 
Polyperythrin,  325. 


Polyuria.  380,  387. 

Portal  vein,  blood  from,  108,  141,  230. 

Potassium  combinations,  elimination  in 
fevers,  383;  in  starvation,  383,  448; 
by  the  urine,  383,  448;  by  the  saliva, 
173;  division  in  the  form  elements 
and  fluids,  53. 

Potassium  chlorate,  poisoning  with, 
114,  401. 

Potassium  phosphate,  in  yolk  ef  the 
egg,  294;  muscles,  263;  cells  53. 

Preputial  secretion,  326. 

Principal  cells,  175,  186. 

Propepsin,  186. 

Propyl -benzol,  in  body,  393. 

Prostatic  calculi,  287. 

Prostatic  secretion,  285. 

Protagon,  273,  274,  275. 

Protamiu,  287. 

Proteid,  31;  of  the  mammary  glands, 
300,  319,  320;  in  the  protoplasm,  43, 
43. 

Proteids,  separation  from  liquids,  31; 
approximate  estimation  in  the,  400; 
influence  on  the  formation  of  gly- 
cogen, 140;  living  and  dead,  4;  de- 
tection, 30;  in  urine,  394-398;  quan- 
titative estimation,  21;  in  the  urine, 
399;  absorption,  227,  229;  passage 
into  the  urine,  394-399;  heat  of  com- 
bustion, 471-473;  digestibility  of,  in 
gastric  juice,  183,  183,  190. 

Protein  bodies,  13-40  (see  various 
bodies). 

Protic  acid,  356. 

Protocatechinic  acid,  in  body,  365. 

Protoplasm,  43,  52,  53. 

Pseudocerebrin,  276,  277. 

Pseudomucin,  34;  properties,  289. 

Pseud oxan thin,  258. 

Purple,  335. 

Purple  cruorin,  73. 

Pus,  127-130;  blue  pus,  130;  pus  in 
urine,  404. 

Pus-cells,  127,  128. 

Pus-serum,  137. 


606 


INDEX. 


Putrefaction  processes,  4  ;  in  intestines, 
316-232,  363-369  ;  regulation  of  the 
putrefaction  in  the  intestines,  230, 
231. 

Putrescin,  376,  435. 

Ptomaines,  11  ;  in  urine,  376. 

Ptyalin,  171  ;  behavior  with  HCl,  173, 
174,  313  ;  action  on  starch,  171. 

Pyaemia,  113. 

Pyin,  14,  133,  138,  130. 

Pyinic  acid,  130. 

Pyloric  glands,  175,  185. 

Pyloric  secretion,  186. 

Pyocyauin,  180  ;  in  sweat,  328. 

Pyoxanthose,  130. 

Pyridin,  in  body,  393. 

Pyrocatechin,  properties,  365 ;  occur- 
rence in  the  urine,  365  ;  in  the  supra- 
renal body,  134 ;  in  transudations, 
125. 

Pyrocatechin -sulphuric  acid,  363,  365. 

Pjj^romucic  acid,  389. 

Pyromucin-ornithuric  acid,  389. 

Pyromucuric  acid,  389. 

Quinic  acid,  behavior  in  the  body,  360. 

Quinin,  passage  into  the  urine,  393  ;  in 
sweat,  338  ;  action  on  the  elimination 
of  uric  acid,  352,  353  ;  on  the  spleen, 
133,  353. 

Rachitis,  240,  241. 

Reduction  processes,  1,  3,  6,  7,  95,  96, 
153,  155.  156,  218,  250,  360,  369,  370, 
390. 

Reducing  substances,  production  in 
putrefaction  and  fermentation,  4, 
218 ;  occurrence  in  blood,  4,  63,  318  ; 
in  urine,  374  ;  in  transudations,  132. 

Rennet,  175-177  ;  properties,  184  ;  de- 
tection in  the  contents  of  the  stom- 
ach, 193  ;  passage  into  the  urine,  376. 

Rennet-cells,  175. 

Rennet-glands,  175. 

Rennet-zymogen,  184. 


Resinous  acids,  passage  into  the  urine, 

393,  396. 
Respiration,  of  the  hen's  egg,  297 ;  of 

plants,  2  (see  Exchange  of  gases). 
Respiratory  quotient,  447. 
Rest,  exchange    of   material,  364-270, 

467,  468.       . 
Retina,  380. 
Rhodophan,  383. 
Rhodopsin,  380. 

Rhubarb,  action  on  the  urine,  394. 
Rigor  mortis  of  the  muscles,  363,  373. 
Robert's  method  for  determining  the 

quantity  of  sugar,  418. 
Rodents,  biliary  acids  of,  147,  158. 
Rods  of  the  retina,    coloring  matter, 

280. 
Rotida's   hyaline    substance,   67,  89, 

139. 

Saccharogen,  in  the  mammary  glands, 
330. 

Saccharic  acid,  374. 

Sal  ammonia,  action  on  the  exchange 
of  material,  466. 

Salicylic  acid,  in  the  body,  393;  action 
on  the  pepsin  digestion,  181;  on  the 
exchange  of  material,  466;  on  trypsin 
digestion,  306. 

Saliva,  168-174;  secretion,  174;  poi- 
sonous properties,  11;  mixed  saliva, 
170,  physiological  importance,  174; 
behavior  in  the  stomach,  174,  187; 
various  kinds,  168-170  ;  action,  170; 
composition,  173. 

Salivary  calculi,  174. 

Salivary  diastase,  see  Ptyalin. 

Salivary  glands,  165. 

Salmon,  flesh,  371;  sperma  of,  287. 

Salts,  see  various  salts. 

Salt-plasma,  55. 

Saltpetre,  action  on  the  exchange  of 
material,  466. 

Samandarin,  336. 

Santonin,  action  on  the  urine,  394,  406. 


INDEX. 


507 


Saponification  of  fat,  203,  213,  244. 

Sarcolactic  acid,  see  Paralactic  acid. 

Sarcolemma,  251. 

Sarcosin,  257;  beliavior  in  the  body, 
389. 

Sarkin,  see  Hypoxanthin. 

Schreiner's  base,  286. 

Sclerotica,  288. 

Scyllit,  131. 

Sebacic  acid,  246. 

Sebum,  326. 

Sediments,  see  Urinary  sediments. 

Sedimentum  lateritium,  333,  354. 

Semen,  285. 

Semen-libres,  285,  286. 

Semigluliu,  38. 

Serum,  see  Blood-serum. 

Serum-albumiu,  14,  56  ;  properties,  60; 
detection  in  urine,  397  ;  quautitative 
estimation,  61,  399  ;  behavior  in  the 
body,  60. 

Serum-casein,  see  Serum-globulin. 

Serum-fibrinogen,  62. 

Serum-globuliu,  14,  56,  59;  importance 
for  the  coagulation  of  the  blood,  90  ; 
properties,  59  ;  detection  in  the  urine, 
397  ;  quantitative  estimation,  60,  400. 

Senna,  action  on  the  urine,  394,  406. 

Sericin,  39. 

Sericoin,  39. 

Serin,  39. 

Serous  fluids,  121-127. 

Shell-membrane  of  the  egg,  35,  296. 

Sheep's  milk,  312. 

Silicic  acid,  in  feathers,  322;  in  urine, 
385;  in  hen's  egg,  294,  296. 

Sinkalin,  44. 

Skatol,  216;  properties,  217;  formation 
in  putrefaction,  216,  363,  368;  be- 
havior in  the  body,  217,  363,  368, 
393. 

Skatol-carbonic  acid,  368. 

Skatol  coloring  matters,  368. 

Skatoxyl,  216.  368. 

Skatoxyl-glycuronic  acid,  368,  393. 


Skatoxyl-sulphuric  acid,  363,  368;  in 
sweat,  327. 

Skin,  322-329;  secretion  by  the  same, 
326-329,  437,  440. 

Sleep,  exchange  of  material,  468. 

Smegma  praeputii,  326. 

Soaps,  in  blood-seium,  62;  chyle,  118; 
pus,  129;  excrements,  222,  Ji23;  bile, 
156;  importance  for  the  emulsihca- 
tion  of  fats,  214,  244. 

Sodium  combinations,  elimination  by 
the  urine,  383;  division  among  form 
elements  and  juices,  53  (see  various 
tissues  and  fluids). 

Sodium  chloride,  elimination  by  the 
urine,  65,  377;  by  the  sweat,  328;  im- 
portance physiologically,  451;  influ- 
ence on  the  quantity  of  urine,  466; 
on  the  elimination  of  urea,  337;  on 
the  secretion  of  gastric  juice,  176; 
quautitative  estimation,  377-379; 
lack  of,  451. 

Sodium  phosphate  in  urine,  380;  action 
on   the  exchange  of  material,   466. 

Sodium  salicylate,  action  on  the  secre- 
tion of  bile,  144. 

Sodium  sulphate,  absorption,  232;  ac- 
tion on  the  metabolism,  466. 

Spectro-photometric  method,  81,  82. 

Spermaceti,  250. 

Spermatin,  287. 

Spermatocele-fluid,  125. 

Spermatozoa,  286. 

Spermine  crystals,  286. 

Spirographin,  34. 

Spleen,  130;  relation  to  the  formation 
of  blood,  132;  to  the  formation  of 
uric  acid,  132,  353;  to  digestion,  132; 
blood  of,  109. 

Splitting  processes,  general,  1,  2,  7  (see 
various  enzymes  and  ferments). 

Spougin,  14,  39. 

Staphylococcus,  behavior  in  gastric 
juice,  192. 

Starch,  hydrolytic  splitting,  by  iutes- 


508 


INDEX. 


tinal    juice,    197;    pancreatic    juice, 

201;  saliva,  171,  174;  behavior  in  the 

stomach,  187. 
Starvation,  action  on  the  blood,  110, 115; 

on  the  secretion  of  bile,  143;  secretion 

ofiiidican,  219,  366;  pancreatic  juice, 

199;  on  the  elimination  of  phenol,  319; 

on  the  exchange  of  material,  443-449. 
Starvation  cures,  480-482. 
Starvation  diabetes,  407. 
Stearic  acid,  244. 
Stearin,  243,  244. 
Stercobilin,  153,  223. 
Stethal,  250. 
Stomach,  importance  of,  in  digestion, 

191;  self -digestion,  192;  digestion  in 

the  stomach,  186-191. 
Stomach,  catarrh,  193. 
Stomach,  contents  of,  see  Chyme. 
Stomach-fistula,  175. 
Stomach,  glands  of,  175. 
Slomach,  mucous  membrane  of,  175. 
Stomach-saliva,  see  Pancreatic  juice. 
Streptococcus,  behavior  in  gastric  juice, 

192. 
Stroma  of  the  blood-corpuscles,  66;  of 

the  muscles,  255 
Stromafibrin,  67. 

Strychnin,  passage  into  the  urine,  393. 
Sublingual  saliva,  169. 
Sublingual  gland,  167. 
Submaxillary  gland,  167. 
Submaxillary  mucin,  32. 
Submaxillary  saliva,  168. 
Succinic  acid,  in  transudations,  121-126; 

in  spleen,  131;  in  thyroid  gland,  133; 

passage  into  the  urine,  374;  in  sweat, 

328. 
Sugar,  formation,  in  the  liver,  141,  142; 

after  the  extirpation  of  the  pancreas, 

407. 
Sugar,  in  stomach,  188;  absorption,  229, 

231,  232;  relation  to  muscular  activ- 
ity, 265-268  (see  various  varieties  of 

sugar). 


Sugar  test  in  the  urine,  411. 

Sulphur,  in  albuminous  bodies,  15;  in 
urine,  neutral  or  acid,  376. 

Sulphur-methsemoglobin,  75. 

Sulphocyanide  of  potassium,  in  saliva, 
169,  170,  173;  in  urine,  376. 

Sulphuric  acid,  ethereal  and  sulphate 
sulphuric  acid;  in  urine,  363;  estima- 
tion, 382;  in  sweat,  328;  elimination 
by  the  urine,  363;  relationship  to  the 
elimination  of  nitrogen,  382,  441. 

Sulphurous  acid  in  the  urine,  376,  389. 

Sulphuretted  hydrogen,  in  intestinal 
putrefaction,  216,  218;  in  urine,  376. 

Supra-renal  body,  134. 

Sweat,  326;  secretion,  327;  action  on 
the  urine,  333,  335,  386,  387. 

Synovial  fluid,  126. 

Syntheses.  1,  2,  7,  135,  140,  217,  248, 
249,  336,  350,  360,  363,  366,  390,  392. 

Syntonin,  24;  from  muscles,  256. 

Sympathetic  saliva,  168. 

Tartaric  acid,  328.    , 

Tartar,  174. 

Tatalbumin,  294. 

Taurin,  151 ;  behavior  in  the  body,  389. 

Taurocarbaminic  acid,  389. 

Taurocholic  acid,  147,  148;  quantity  in 
various  animal  biles,  158;  decompo- 
sition in  the  intestines,  219. 

Tea,  action  on  the  exchange  of  material, 
467. 

Tears,  283. 

Teeth,  241. 

Teichm ANN'S  crystals,  78,  79. 

Tension  of  the  carbon  dioxide  in  blood, 
102-105;  in  the  lymph,  118;  of  the 
oxygen  in  the  blood,  100-102. 

Terpentine,  action  on  the  secretion  of 
bile,  144  ;  on  the  urine,  394  ;  behav- 
ior in  the  body,  375. 

Terpenglycuronic  acid,  375. 

Testicles,  285. 

Tetanin.  11. 


INDEX. 


509 


Tetronerythrin,  83,  325. 

Tballin,  action  on  the  urine,  394. 

Theobromin,  48. 

Theophyllin,  48. 

Tbyieoprotein ,  133. 

Tbyroidea,  133. 

Thyroid  gland,  133. 

Thymus,  132. 

Tissue-fibrinogen,  88,  90. 

Tissue-proteids,  457,  458. 

Toluic  acid,  392. 

Toluricacid,  393. 

Toluol,  behavior  in  the  body,  360, 
391. 

Toluylendiamin-poisoning,  162. 

Tonus,  chemical,  of  the  muscles,  264, 
469. 

Tortoise-shell,  35. 

Toxine,  11. 

Transudations,  117,  121-127. 

Transudations  in  the  intestine,  225. 

Tribrom-acetic  acid,  17. 

Tribromamido-benzoic  acid,  17. 

Trichlorbutyl-alcohol,  behavior  in  the 
body,  390. 

Trichlorbutyl-glycuronic  acid,  390. 

Tricblorethyl-glycuronic  acid,  390. 

Triuitroalbumin,  17. 

Triolein,  245. 

Tripalmitin,  245. 

Triple  phosphate,  in  urinary  sediments, 
430;  in  urinary  calculi,  430,  432. 

Tristearin,  245. 

Tuommer's  sugar  test,  409,  411 :  behav- 
ior to  glycuronic  acid,  375;  uric 
acid,  354;  creatinin,  348. 

Tuberculosis  virus,  behavior  with  gas- 
tric juice,  192. 

Tubo-ovarial  cysts,  291. 

Tunicin,  32-3. 

Turacoverdin,  325. 

Turacin,  325. 

Trypsin,  201,  204;  action  on  proteids, 
205:  on  other  bodies,  38,  210,  211. 

Trypsin  digestion,  influence  of  various 


conditions  on  the  same,  205,  206; 
products,  206. 

Trypsin-zymogen,  200,  211,  212. 

Typhotoxin,  11. 

Tyrosin,  properties  and  occurrence, 
208;  in  urine,  424;  in  sediments,  424, 
430:  detection,  209,  424;  origin,  16, 
35,  206,  216;  behavior  in  putrefac- 
tion, 360.  363;  in  the  body,  391,  39:.'. 

Tyrosin-sulphuric  acid,  232. 

Uraemia,  blood,  115;  bile,  158;  contents 
of  the  stomach,  193;  sweat,  328. 

Uramido-acids,  328. 

Urates,  354;  in  sediments,  332,  428. 

Urea,  336;  elimination  in  activity  and 
in  rest,  267,  268,  467,  468;  in  starva- 
tion, 444;  in  children,  470;  in  disease, 
337,    338,  383;   after  various  foods. 

337,  454-467;  secretion  of  urea  after 
meals,  458;  properties  and  reactions, 
339,  340;  formation  in  the  organism, 

338,  339;  quantitative  estimation,  341- 
347;  splitting  by  ferments,  340,  427; 
synthesis,  336,  338;  occurrence,  337. 

Ureids,  16. 

Ureometer,  of  Esbach,  346  ;  of  Dore- 
Mus,  346. 

Uric  acid.  350;  relation  to  urea,  350. 
351;  properties  and  reactions,  353, 
354;  formation  in  the  body,  352,  353: 
relation  of  the  spleen  to  the  same 
132,  352;  quantitative  estimation, 
355,  356;  synthesis,  350;  behavior  i?j 
the  body,  351;  occurrence,  351;  in 
sweat,  328;  in  sediments,  332,  427, 
428. 

Uric-acid  calculi,  431. 

Uric-acid  sediments,  332,  426-430. 

Urine,  330-433;  secretion,  385,  386. 
constituents,  inorganic,  377-385; 
poisonous,  11.  376;  organic,  patho- 
logical, 394-426;  physiological.  336- 
377;  casual,  388-396;  color,  332,  369, 
388.   394,  405,   406;  solids,  calcula- 


510 


INDEX. 


tions  of  the  same,  387;  fermentation, 
alkaline,  374,  437;  acid  fermentation, 
427;  gases,  385;  quantity,  386,  387, 
388;  physical  properties,  831-336; 
reactiou,  332,  427;  degree  of  acidity, 
332,  333;  determination  of  acidity, 
334;  specific  gravity,  335-387;  deter- 
mination of,  336;  passage  of  foreign 
bodies,  388-394;  composition,  388. 

Urinary  calculi,  430-433. 

Urinary  coloring  matters,  369-374,  405, 
406. 

Urinary  indican,  466,  467. 

Urinary  indigo,  466,  467. 

Urinary  sand,  430. 

Uriuometer,  336. 

Urobilin,  370,  371;  relation  to  bilirubin, 
153,  161,  370;  to  choletelin,  371;  to 
haematin,  161.  162,  371;  to  haemato- 
porphyrin,  371;  to  hydrobilirubin, 
371;  properties,  370-373. 

Urobilin  icterus,  371. 

Urobilinogen,  369,  370. 

Urobilinoidin,  371. 

Urocanic  acid,  377. 

Urochloralic  acid,  390. 

Urochrora,  373. 

Urocyanin,  370. 

Uroerythrin,  373,  403. 

Urofuscohsematin,  403. 

Uro.u^laucin,  870. 

Urohaematin,  3T0,  404 

Urohodin,  370. 

Uroleucic  acid,  365. 

Uiomelanine,  370. 

Urophsein,  370. 

Urorosein,  370,  403. 

Urorubin,  370. 

Urorubrohsematin,  403. 

Urostealith  stone,  433. 

Uroxanthin,  366. 

Uterine  milk,  298. 

Valerianic  acid.  16,  243. 

Vegetable  acids,salts  of,  in  the  urine,334. 


Vegetarians,  nutrition,  476;  excrement, 

222. 
Vernix  caseosa,  326. 
Visual  red,  280. 
Visual  purple,  280. 
Vitellin,  14;  in  the  egg-yolk,  392;  in 

the  protoplasm,  42. 
Vitellolutein,  294. 
Vitellorubin,  294. 
Vitelloses,  27. 
Vitreous  humor,  234,  282. 

Water,  drinking,  action  on  the  elimina- 
tion of  chlorides,  377;  of  urea,  337, 
465;  on  the  accumulation  of  fat,  465; 
on  the  secretion  of  bile,  144;  on  the 
secretion  of  urine,  385-387. 

"Water,  elimination  by  the  urine, 
385-387,  438;  by  the  skin,  327,  438; 
in  starvation,  447;  importance  for  the 
body,  449;  amount  of,  in  the  organs, 
449;  lack  of  water  in  the  nutrition, 
449. 

Whey,  312. 

Whey  albumin,  305. 

White  of  the  hen's  egg,  294. 

Witch's  milk,  316. 

Woman's  milk,  see  Human  milk. 

Wool-fat,  326. 

Work,  influence  of,  on  the  elimination 
of  chlorine,  377;  on  the  exchange  of 
material,  267,  269,  467,  468. 

Xanthin,  properties  and  occurrence, 
49;  in  urine,  359;  in  urinary  sedi- 
ments, 430;  quantity  in  the  liver,  137; 
in  pancreas,  200;  detection  and  quan- 
titative estimation,  51,  52,  359. 

Xanthin  bodies,  general  on  the  impor- 
tance and  occurrence,  47,  48;  in  blood 
in  leucaemia,  48;  in  urine,  359;  rela- 
tion to  muscular  activity,  269;  steps 
to  the  formation  of  uric  acid,  353. 

Xanthin  stones,  433. 

Xunthocreatinin,  258,  350. 


INDEX. 


511 


Xanthophan,  282. 
Xanthoproteic  acid,  17,  20. 
X.'intboproteic-acid  reaction,  20. 
Xylol,  behavior  in  the  body,  392. 

Yolk,  of  hen's  egg,  291. 
Tolk,  membrane,  291. 


Zinc,  is  the  liver,  137;  passage  into  the 
milk,  320. 

Zooerythrin,  325. 

Zoofulvin,  325. 

Zoorubin,  325. 

Zymogens,  see  various  enzymes:  Ren- 
net, Pepsin,  and  Pancreatic  enzyme. 


SPECTEUM    PLATE. 

1.  Absorption  spectrum  of  a  solution  of  oxyhcemogloMn. 

3.  Absorption  spectrum  of  a  solution  of  hmmoglobin,  obtained  by  the  action  of 
an  ammoniacal  ferro-tartrate  solution  on  an  oxyhgemoglobin  solution. 

3.  Absorption  spectrum  of  a  faintly-alkaline  solution  of  methmmoglobin. 

4.  Absorption  spectrum  of  a  solution  of  TioBmaUn  in  ether  containing  oxalic 

acid. 

5.  Absorption  spectrum  of  an  alkaline  solution  of  Jimmatin. 

6.  Absorption  spectrum  of  an  alkaline  solution  of  Jimmochromogen,  obtained  by 

the  action   of    an    ammoniacal   ferro-tartrate   solution  on  an   alkaline- 
hsematin  solution. 

7.  Absorption  spectrum  of  an  acid  solution  of  urobilin. 

8.  Absorption  spectrum  of  an  alkaline  solution  of  urohilin  after  the  addition  of 

a  zinc-chloride  solution . 

9.  Absorption  spectrum  of  a  solution  of  lutein  (ethereal  extract  of  the  egg-yolk). 


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